Triarylamine derivative, light-emitting substance, light-emitting element, light-emitting device, and electronic device

ABSTRACT

A triarylamine derivative represented by a general formula (G1) given below is provided. Note that in the formula, Ar represents either a substituted or unsubstituted phenyl group or a substituted or unsubstituted biphenyl group; α represents a substituted or unsubstituted naphthyl group; β represents either hydrogen or a substituted or unsubstituted naphthyl group; n and m each independently represent 1 or 2; and R 1  to R 8  each independently represent any of hydrogen, an alkyl group having 1 to 6 carbon atoms, or a phenyl group.

This application is a continuation of application Ser. No. 14/605,286filed on Jan. 26, 2015 which is a divisional of application Ser. No.13/474,104 filed on May 17, 2012 (now U.S. Pat. No. 8,940,416 issuedJan. 27, 2015) which is a continuation of application Ser. No.12/464,506 filed on May 12, 2009 (now U.S. Pat. No. 8,182,933 issued May22, 2012), which are all incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a triarylamine derivative. In addition,the present invention relates to a light-emitting substance, alight-emitting element, and an electronic device using the triarylaminederivative.

BACKGROUND ART

A display device using a light-emitting element in which an organiccompound is used as a light-emitting substance (an organic EL element)has been developed rapidly as a next generation display device becauseit has advantages such as thinness, lightness in weight, high responsespeed, and low power consumption. Although there have been variousobstacles, technique has been improved such that organic EL televisionshave become commercially available recently.

In an organic EL element, when voltage is applied between a pair ofelectrodes which interpose a light-emitting layer therebetween,electrons and holes injected from the electrodes are recombined to forman excited state, and when the excited state returns to a ground state,light is emitted. A wavelength of light emitted from a light-emittingsubstance is peculiar to the light-emitting substance; thus, by usingdifferent types of organic compounds as light-emitting substances,light-emitting elements which exhibit various wavelengths, i.e., variouscolors can be obtained.

In the case of a display device which is expected to display images,such as a display, at least three colors of light, i.e., red, green, andblue are required to be obtained in order to reproduce full-colorimages. To achieve this, for example, there are following methods: amethod in which a color filter is combined with a light-emitting elementemitting light with a light-emitting spectrum in a wide wavelength, amethod in which a color conversion layer is combined with alight-emitting element emitting light with a wavelength shorter than awavelength of an objective color, and a method in which a light-emittingelement emitting light with a desired wavelength is used. Among thesethree methods, the final one, i.e., a method in which an objective coloris obtained directly is preferable because loss in energy is small inthis method.

This method is employed for the above organic EL televisions which havebecome commercially available; however, actually, in addition to thatmethod, a color filter is used, and a micro cavity structure is employedfor a light-emitting element in order to improve color purity. OrganicEL televisions having got many advantages are naturally expected toprovide high quality images as a next generation television, andlight-emitting elements exhibiting appropriate emission colors arerequired to meet the expectation.

A light emitted from a light-emitting substance is peculiar to thesubstance as described above. There are many measures to improve thecolor purity of an organic EL television, which means that it is verydifficult to obtain a light-emitting element which exhibits lightemission of a favorable color and also satisfies another importantproperty such as a lifetime or power consumption. In addition, animportant property of a light-emitting element, such as a lifetime orpower consumption, does not necessarily depend only on a substanceexhibiting light emission. The property is greatly affected also bylayers other than a light-emitting layer, an element structure, anaffinity between a light-emitting substance and a host, or the like.Therefore, it is true that many kinds of materials are necessary forlight-emitting elements in order to show the growth of this field. As aresult thereof, materials for light-emitting elements which have avariety of molecular structures have been disclosed (for example, seeReference 1).

REFERENCES Patent Document

-   [Reference 1] PCT International Publication No. 07/058,127

DISCLOSURE OF INVENTION

Among light-emitting elements that are developed until now, however,light-emitting elements that emit blue light are inferior incharacteristics to light-emitting elements that emit red light to greenlight, which is a problem. In order to emit blue light, a light-emittingsubstance having a large energy gap is necessary and a substance usedfor a host in which the light-emitting substance is dispersed or asubstance used for a transporting layer adjacent to a light-emittingregion in a light-emitting layer needs to have a larger energy gap,which is one cause of the above problem.

When a material whose energy gap is not large enough is used as a hostmaterial or a material for a layer that is adjacent to a light-emittingregion, exciton energy transfers to the material; thus, there areproblems such as reduction in color purity and luminous efficiency ofthe light-emitting element. Thus, according to one embodiment of thepresent invention, it is an object thereof to provide a noveltriarylamine derivative which has large energy gap and can be used for atransporting layer or a host material of a light-emitting element.

The inventors of the present invention was able to synthesize atriarylamine derivative whose energy gap is large and carriertransporting property is appropriate, in which one or two naphthylgroups are bonded to central nitrogen through a phenylene group or abiphenylene group as a substance that can be used preferably as amaterial of a light-emitting element.

In other words, a triarylamine derivative according to one embodiment ofthe present invention is a triarylamine derivative represented by ageneral formula (G1) given below.

In the formula, Ar represents either a substituted or unsubstitutedphenyl group or a substituted or unsubstituted biphenyl group; αrepresents a substituted or unsubstituted naphthyl group; and βrepresents either hydrogen or a substituted or unsubstituted naphthylgroup. In addition, n and m each independently represent 1 or 2; and R¹to R⁸ each independently represent any of hydrogen, an alkyl grouphaving 1 to 6 carbon atoms, or a phenyl group.

Specifically, as Ar in the formula, groups represented by structuralformulae (Ar-1) to (Ar-4) below are given.

Specifically, as α in the formula, groups represented by structuralformulae (α-1) and (α-2) below are given.

Specifically, as β in the formula, groups represented by structuralformulae (β-1) to (β-3) below are given.

The triarylamine derivative according to one embodiment of the presentinvention having any of the above structural formulae is a noveltriarylamine derivative which has large energy gap and can be used for atransporting layer or a host material of a light-emitting element. Inother words, the triarylamine derivative according to one embodiment ofthe present invention, which has large energy gap or in which there isan energy difference (hereinafter also referred to as triplet energy)between a ground state and a triplet excited state, can be verypreferably used as a host material or a carrier transporting material(especially as a hole transporting material) of a light-emitting elementproviding blue fluorescence or a light-emitting element providing greenphosphoresce. Therefore, the triarylamine derivative according to oneembodiment of the present invention can be used as a host material or acarrier transporting material of a light-emitting substance havingemission wavelengths in a wide visible region (from blue light to redlight), whereby light can be emitted efficiently. In addition, in thecase of a light-emitting device including a plurality of red, green, andblue pixels, a host material or a carrier transporting material can havethe same kind also in a process of forming a light-emitting element;therefore, the process can be simplified and the use efficiency of thematerial is also high, which are preferable.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are conceptual views of light-emitting elements(Embodiments 3 to 5);

FIG. 2 is a conceptual view of an organic semiconductor element(Embodiment 6);

FIGS. 3A and 3B are conceptual views of an active matrix light-emittingdevice (Embodiment 7);

FIGS. 4A and 4B are conceptual views of a passive matrix light-emittingdevice (Embodiment 7);

FIGS. 5A to 5D are views each illustrating an electronic device(Embodiment 8);

FIG. 6 is a view illustrating an electronic device (Embodiment 8);

FIG. 7 is a view illustrating a lighting apparatus (Embodiment 8);

FIG. 8 is a view illustrating a lighting apparatus (Embodiment 8);

FIGS. 9A and 9B are graphs of ¹HNMR charts of αNBA1BP;

FIG. 10 is a graph of absorption spectra of αNBA1BP;

FIG. 11 is a graph of emission spectra of αNBA1BP;

FIGS. 12A and 12B are graphs of ¹H NMR charts of αNBB1BP;

FIG. 13 is a graph of absorption spectra of αNBB1BP;

FIG. 14 is a graph of emission spectra of αNBB1BP;

FIG. 15 is a graph of voltage vs. luminance characteristics of thelight-emitting elements manufactured in Example 9;

FIG. 16 is a graph of luminance vs. current efficiency characteristicsof the light-emitting elements manufactured in Example 9;

FIG. 17 is a graph of luminance vs. power efficiency characteristics ofthe light-emitting elements manufactured in Example 9;

FIG. 18 is a graph of emission spectra of the light-emitting elementsmanufactured in Example 9;

FIG. 19 is a graph of current density vs. luminance characteristics ofthe light-emitting elements manufactured in Example 10;

FIG. 20 is a graph of luminance vs. current efficiency characteristicsof the light-emitting elements manufactured in Example 10;

FIG. 21 is a graph of luminance vs. power efficiency characteristics ofthe light-emitting elements manufactured in Example 10;

FIG. 22 is a graph of voltage vs. luminance characteristics of thelight-emitting elements manufactured in Example 10;

FIG. 23 is a graph of voltage vs. luminance characteristics of thelight-emitting elements manufactured in Example 11;

FIG. 24 is a graph of luminance vs. current efficiency characteristicsof the light-emitting elements manufactured in Example 11;

FIG. 25 is a graph of luminance vs. power efficiency characteristics ofthe light-emitting elements manufactured in Example 11;

FIG. 26 is a graph of emission spectra of the light-emitting elementsmanufactured in Example 11;

FIG. 27 is a graph of time vs. normalized luminance characteristics ofthe light-emitting elements manufactured in Example 11; and

FIG. 28 is a graph of wavelength vs. transmittance characteristics of acomposite material.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described hereinafter.However, the present invention can be implemented in various modes, andit is easily understood by those skilled in the art that modes anddetails thereof can be modified in various ways without departing fromthe spirit and the scope of the present invention. Therefore, thepresent invention should not be interpreted as being limited to thedescription of the embodiments below.

Embodiment 1

A triarylamine derivative in this embodiment is the triarylaminederivative in which the naphthyl group represented by a, which isdescribed above, is bonded to central nitrogen through a phenylene groupor a biphenylene group. The triarylamine derivative has one or twostructures in which the above naphthyl group is bonded to centralnitrogen through a phenylene group or a biphenylene group. When thereare two naphthyl groups, the second naphthyl group corresponds to β inthe above general formula (G1). Note that the substitution positionwhere the second naphthyl group is bonded to a phenylene group or abiphenylene group may be a 1-position or a 2-position. In addition, thenaphthyl group may further have a substituent.

In addition, in the triarylamine derivative in this embodiment, as forone or two bonds among three bonds of the central nitrogen atom, aphenylene group or a biphenylene group, with which a naphthyl group isbonded, is bonded to one or two bonds; and the rest of two or one bondis bonded to a phenyl group or a biphenyl group. In addition, thephenylene group or biphenylene group may further have a substituent.

The triarylamine derivative of this embodiment having such a structurehas an adequate hole transporting property and a wide energy gap at thesame time, and the triarylamine derivative is a substance that can bevery preferably used as a material for a light-emitting element emittingblue light.

The triarylamine derivative of this embodiment as described above canalso be represented by a general formula (G1) given below.

In the formula, Ar represents either a phenyl group or a biphenyl group;α represents a naphthyl group; and β represents either hydrogen or anaphthyl group. Alternatively, the Ar, α, and β each may have anotherone or a plurality of substituents. As the substituent, an alkyl grouphaving 1 to 6 carbon atoms and a phenyl group can be given. Note thatwhen the substituent is an alkyl group having 1 to 6 carbon atoms, notonly a non-cyclic alkyl group but also a cyclic alkyl group may be used.

In addition, n and m each independently represent 1 or 2. In otherwords, when n and m each represent 1, they each represent a phenylenegroup, and when n and m each represent 2, they each represent abiphenylene group. Further, R¹ to R⁸ each independently represent any ofhydrogen, an alkyl group having 1 to 6 carbon atoms, or a phenyl group.When R¹ to R⁸ are each an alkyl group having 1 to 6 carbon atoms, notonly non-cyclic alkyl group but also a cyclic alkyl group may be used.

Note that when n or m represents 2, R¹ to R⁸ may be different between aphenylene group bonded to amine and a phenylene group bonded to thephenylene group. In other words, when n or m represents 2, although thegroup in the parenthesis of the above general formula (G1) is abiphenylene group in which two phenylene groups are bonded, the casewhere the bonded two phenylene groups have different substituents isalso included.

Specifically, as Ar in the formula, groups represented by structuralformulae (Ar-1) to (Ar-4) below are given.

Specifically, as a in the formula, groups represented by structuralformulae (α-1) and (α-2) below are given.

Specifically, as β in the formula, groups represented by structuralformulae (β-1) to (β-3) below are given.

Specifically, as R¹ to R⁸ in the formula, groups represented bystructural formulae (R-1) to (R-9) below are given.

As specific examples of the triarylamine derivative represented by thegeneral formula (G1), there are triarylamine derivatives represented bystructural formulae (1) to (87) given below. However, the presentinvention is not limited to these examples.

The triarylamine derivative in this embodiment as described above, whichhas large energy gap or in which there is an energy difference(hereinafter also referred to as triplet energy) between a ground stateand a triplet excited state, can be very preferably used as a hostmaterial or a carrier transporting material (especially as a holetransporting material) of a light-emitting element providing bluefluorescence or a light-emitting element providing green phosphoresce.Therefore, the triarylamine derivative in this embodiment can be used asa host material or a carrier transporting material of a light-emittingsubstance having emission wavelengths in a wide visible region (fromblue light to red light), whereby light can be emitted efficiently. Inaddition, in the case of a light-emitting device including a pluralityof red, green, and blue pixels, a host material or a carriertransporting material can have the same kind also in a process offorming a light-emitting element; therefore, the process can besimplified and the use efficiency of the material is also high, whichare preferable.

Embodiment 2

Subsequently, a synthetic method of the triarylamine derivativedescribed in Embodiment 1 will be shown in this embodiment.

<Synthetic Method 1>

In this synthetic method, the following compound M which is thetriarylamine derivative described in Embodiment 1 is synthesized by twomethods, <Synthetic Method 1-1> and <Synthetic Method 1-2>. First, theabove compound M is synthesized by Reaction Scheme (A-1) in thissynthetic method. Reaction Scheme (A-1) shows a synthetic method of theabove compound M through coupling with secondary arylamine (a compoundD1) and coupling with an arylboronic acid, with dihalogenated aryl (acompound E2) used as a starting material. Note that the compound D1 issecondary arylamine in which an aryl group represented by Ar and an arylgroup having β are bonded to central nitrogen.

In the synthetic method by Reaction Scheme (A-1), either the secondaryarylamine (the compound D1) or an arylboronic acid may be coupled firstwith the halogenated aryl (the compound E2).

<Synthetic Method 1-1>

Here, a method in which the dihalogenated aryl (the compound E2) and thesecondary arylamine (the compound D1) are coupled to synthesize tertiaryarylamine and then the tertiary arylamine is coupled with an arylboronicacid is shown.

In order to couple the secondary arylamine (the compound D1) and thehalogenated aryl (the compound E2), a synthetic method using a metalcatalyst in the presence of a base can be applied. Accordingly, acompound A2 which is tertiary arylamine can be synthesized. The compoundA2 is tertiary arylamine in which an aryl group represented by Ar, anaryl group having 3, and an aryl group having a halogen grouprepresented by X are bonded to central nitrogen.

The case of using a Buchwald-Hartwig reaction in the above reaction isshown. As a palladium catalyst which can be used as a metal catalyst,bis(dibenzylideneacetone)palladium(0), palladium(II) acetate, and thelike can be given. As a ligand in the above palladium catalyst,tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine,1,1-bis(diphenylphosphino)ferrocene (abbreviation: DPPF), and the likecan be given. As a substance which can be used as the base, an organicbase such as sodium tert-butoxide, an inorganic base such as potassiumcarbonate, and the like can be given. In addition, the above reaction ispreferably performed in a solution, and toluene, xylene, benzene, andthe like can be given as a solvent that can be used in the abovereaction. However, the catalyst, ligand, base, and solvent which can beused are not limited thereto.

The case of using the Ullmann reaction in the above reaction is shown. Acopper catalyst can be used as the metal catalyst, and copper iodide (1)and copper acetate (II) can be given as the copper catalyst. As asubstance that can be used as the base, an inorganic base such aspotassium carbonate can be given. The above reaction is preferablyperformed in a solution, and1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (abbreviation: DMPU),toluene, xylene, benzene, and the like can be given as a solvent thatcan be used in the above reaction. However, the catalyst, base, andsolvent which can be used are not limited thereto.

DMPU or xylene which has a high boiling point is preferably used as thebase because, by an Ullmann reaction, an object can be obtained in ashorter time and at a higher yield when the reaction temperature isgreater than or equal to 100° C. Since it is further preferable that thereaction temperature be a temperature greater than or equal to 150° C.,DMPU is more preferably used.

The tertiary arylamine (the compound A2) having a halogen group, whichis obtained as described above, is coupled with the arylboronic acidusing a metal catalyst in the presence of a base, so that the compound Mwhich is the triarylamine derivative described in Embodiment 1 can besynthesized. As for the arylboronic acid, an arylboronic acid having anaryl group represented by a is used.

As described above, as a reaction in which the tertiary arylamine (thecompound A2) having a halogen group is coupled with the arylboronicacid, there are various reactions. As an example thereof, aSuzuki-Miyaura reaction can be given.

The case of performing a Suzuki-Miyaura reaction in the above reactionis described. As a palladium catalyst which can be used as a metalcatalyst, palladium(II) acetate,tetrakis(triphenylphosphine)palladium(0),bis(triphenylphosphine)palladium(II)dichloride, and the like can begiven. As a ligand in the above palladium catalyst,tri(ortho-tolyl)phosphine, triphenylphosphine, tricyclohexylphosphine,and the like can be given. In addition, as the above base, an organicbase such as sodium tert-butoxide, an inorganic base such as potassiumcarbonate, and the like can be given. The reaction is preferablyperformed in a solution, and as the solvent which can be used, a mixedsolvent of toluene and water, a mixed solvent of toluene, an alcoholsuch as ethanol, and water, a mixed solvent of xylene and water, a mixedsolvent of xylene, an alcohol such as ethanol, and water, a mixedsolvent of benzene and water, a mixed solvent of benzene, an alcoholsuch as ethanol, and water, a mixed solvent of ethers such asethyleneglycoldimethylether and water, and the like can be given.However, the catalyst, ligand, base, and solvent which can be used arenot limited thereto. In addition, in the above scheme, organoaluminum,organozirconium, organozinc, organotin compound, or the like may be usedinstead of an arylboronic acid.

<Synthetic Method 1-2>

In this synthetic method, a method in which the dihalogenated aryl (thecompound E2) and an arylboronic acid are coupled first to synthesizemonohalogenated aryl (a compound E1) and then the monohalogenated aryl(the compound E1) is coupled with the secondary arylamine (the compoundD1) is shown. Note that in this reaction, as for the arylboronic acid,an arylboronic acid having an aryl group represented by a is used.

In order to couple the dihalogenated aryl (the compound E2) and thearylboronic acid, a reaction may be performed using a metal catalyst inthe presence of a base. As a reaction example, a Suzuki-Miyaura reactioncan be given. In the case of performing the reaction by using aSuzuki-Miyaura reaction, the synthesis is performed in a manner similarto that of the synthesis described in Synthetic Method 1-1. Since thedescription on the synthetic method will be repeated, the detaileddescription is omitted and the description on a Suzuki-Miyaura reactionin Synthetic Method 1-1 is to be referred. Through this reaction, thecompound E1 which is a monohalogenated aryl having a substituent α canbe synthesized.

After that, the synthesized monohalogenated aryl (the compound E1) andthe secondary arylamine (the compound D1) are coupled using a metalcatalyst in the presence of a base, so that the compound M which is thetriarylamine derivative described in Embodiment 1 can be synthesized. Asa coupling reaction used for the reaction, there are various reactions.As a typical example thereof; a Buchwald-Hartwig reaction, an Ullmannreaction, and the like can be given. The detailed description on thereaction using a Buchwald-Hartwig reaction or an Ullmann reaction ismade in Synthetic Method 1-1, and this reaction can also be performed ina similar manner. Therefore, since the description on the syntheticmethod will be repeated, the description is omitted and the descriptionson a Buchwald-Hartwig reaction and Ullmann reaction in Synthetic Method1-1 are to be referred.

<Synthetic Method 2>

In this synthetic method, the following compound M which is thetriarylamine derivative described in Embodiment 1 is synthesized byReaction Scheme (A-2). Reaction Scheme (A-2) shows a synthetic method ofthe above compound M in which, with secondary arylamine (a compound B3)used as a starting material, a substance (a compound B1) that is coupledwith an arylboronic acid is coupled with halogenated aryl after the endgroup of an aryl group of the compound B3 is halogenated.

In this Reaction Scheme (A-2), hydrogen at the end group of an arylgroup of the compound B3 which is secondary arylamine having asubstituent β is first halogenated using a halogenating agent to obtainhalide (a compound B2) of secondary arylamine having a substituent β. Asthe halogenating agent, N-Bromosuccinimide (abbreviation: NBS),N-Iodosuccinimide (abbreviation: NIS), bromine, iodine, potassiumiodide, or the like can be used. As the halogenating agent, the use of abromide such as N-Bromosuccinimide (abbreviation: NBS) or bromine ispreferable because synthesis can be performed at low cost.

Subsequently, the compound B2 and the arylboronic acid are coupled tosynthesize secondary arylamine represented by the compound B. In orderto couple the secondary arylamine (the compound B2) having a halogengroup and the arylboronic acid, a reaction may be performed using ametal catalyst in the presence of a base. As a reaction example, aSuzuki-Miyaura reaction can be given. In the case of performing thereaction by using a Suzuki-Miyaura reaction, the synthesis is performedin a manner similar to that of the synthesis described in SyntheticMethod 1-1. Since the description on the synthetic method will berepeated, the detailed description is omitted and the description on aSuzuki-Miyaura reaction in Synthetic Method 1-1 is to be referred.Through this reaction, the compound B1 which is the secondary arylaminehaving a substituent ac and a substituent β can be synthesized. Notethat as the halogenating agent for the halogenation, it is preferable touse an iodide such as N-Iodosuccinimide (abbreviation: NIS), iodine, orpotassium iodide and select iodine as a halogen for substitution becausethis coupling reaction occurs efficiently in a shorter time.

Next, the Compound B1 which is the secondary arylamine and halogenatedaryl represented by a compound C1 are coupled, so that the compound Mwhich is the triarylamine derivative described in Embodiment 1 can besynthesized. As a coupling reaction used for the reaction, there arevarious reactions. As a typical example thereof, a Buchwald-Hartwigreaction, an Ullmann reaction, and the like can be given. The detaileddescription on the reaction using a Buchwald-Hartwig reaction or anUllmann reaction is made in Synthetic Method 1-1, and this reaction canalso be performed in a similar manner. Therefore, since the descriptionon the synthetic method will be repeated, the description is omitted andthe descriptions on a Buchwald-Hartwig reaction and Ullmann reaction inSynthetic Method 1-1 are to be referred.

Note that as described above, the compound B1 can be obtained byhalogenating the secondary arylamine (the compound B3) and being coupledwith the arylboronic acid. Alternatively, as in Reaction Scheme (A-3),there is a method in which synthesis is performed by coupling primaryarylamine (a compound S1) and the monohalogenated aryl (the compoundE1). As a coupling reaction used for the reaction, there are variousreactions. As a typical example thereof; a Buchwald-Hartwig reaction, anUllmann reaction, and the like can be given. The detailed description onthe reaction using a Buchwald-Hartwig reaction or an Ullmann reaction ismade in Synthetic Method 1-1, and this reaction can also be performed ina similar manner. Therefore, since the description on the syntheticmethod will be repeated, the description is omitted and the descriptionson a Buchwald-Hartwig reaction and Ullmann reaction in Synthetic Method1-1 are to be referred.

Note that when a Buchwald-Hartwig reaction is used for the synthesis ofthe above secondary arylamine (the compound B1), the primary arylamine(the compound S1) and the halogenated aryl can be reacted with a highyield in an equivalent of 1:1, which is preferable.

<Synthetic Method 3>

In this synthetic method, the following compound M which is thetriarylamine derivative described in Embodiment 1 is synthesized byReaction Scheme (A-4). Reaction Scheme (A-4) shows a synthetic method ofthe compound M in which, with tertiary arylamine (a compound A3) used asa starting material, boron oxidation is performed and a substance (acompound A1) on which the boron oxidation is performed is coupled withhalogenated aryl after the end group of an aryl group of the compound A3is halogenated.

The tertiary arylamine (the compound A3) is a compound in which aportion represented by α in the compound M, which is the triarylaminederivative described in Embodiment 1, is hydrogen. Therefore, byhalogenating the hydrogen portion, the halogenated aryl (the compoundA2) in which the portion represented by α in the compound M is halogencan be synthesized. The halogenation can be performed using ahalogenating agent. As the halogenating agent, N-Bromosuccinimide(abbreviation: NBS), N-Iodosuccinimide (abbreviation: NIS), bromine,iodine, potassium iodide, or the like can be used. As the halogenatingagent, the use of a bromide such as N-Bromosuccinimide (abbreviation:NBS) or bromine is preferable because synthesis can be performed at lowcost.

Subsequently, boron oxidation of the obtained halogenated aryl (thecompound A2) is performed to synthesize arylboronic acid (the compoundA1). Synthesis of the arylboronic acid (the compound A1) can beperformed by a method using organolithium and organoboronic acid. Inaddition, n-butyllithium, methyllithium, or the like can be used as theorganolithium. Trimethyl borate, isopropyl borate, or the like can beused as the organoboronic acid.

After that, the synthesized arylboronic acid (the compound A1) iscoupled with the halogenated aryl in which an aryl group represented bya and a halogen are bonded, so that the compound M which is thetriarylamine derivative described in Embodiment 1 can be synthesized. Inorder to couple the arylboronic acid (the compound A1) with thehalogenated aryl in which an aryl group represented by a and a halogenare bonded, a reaction may be performed using a metal catalyst in thepresence of a base. As a reaction example, a Suzuki-Miyaura reaction canbe given. In the case of performing the reaction by using aSuzuki-Miyaura reaction, the synthesis is performed in a manner similarto that of the synthesis described in Synthetic Method 1-1. Since thedescription on the synthetic method will be repeated, the detaileddescription is omitted and the description on a Suzuki-Miyaura reactionin Synthetic Method 1-1 is to be referred. Note that as the halogenatingagent for the halogenation, it is preferable to use an iodide such asN-Iodosuccinimide (abbreviation: NIS), iodine, or potassium iodide andselect iodine as a halogen for substitution because this couplingreaction occurs efficiently in a shorter time.

In the following Reaction Scheme (A-5), a synthetic method of thecompound A3 which is used as a starting material of Reaction Scheme(A-4) will be shown. In this Reaction Scheme (A-5), although thefollowing methods are shown, the synthetic method of the compound A3 isnot limited thereto: a method of coupling the secondary arylamine (thecompound B3) and the halogenated aryl (the compound C1); a method ofcoupling the secondary arylamine (the compound D1) and halogenated aryl(a compound E3); and a method of coupling two kinds of halogenated aryl(the compound C1 and a compound F1) and primary arylamine (a compoundG1).

For the above coupling reaction, a coupling reaction using a metalcatalyst can be used. As such a reaction, there are various reactions.As a typical example thereof, a Buchwald-Hartwig reaction, an Ullmannreaction, and the like can be given. The detailed description on thereaction using a Buchwald-Hartwig reaction or an Ullmann reaction ismade in Synthetic Method 1-1, and this reaction can also be performed ina similar manner. Therefore, since the description on the syntheticmethod will be repeated, the description is omitted and the descriptionson a Buchwald-Hartwig reaction and Ullmann reaction in Synthetic Method1-1 are to be referred. Note that in the method of coupling the twokinds of halogenated aryl (the compound C1 and the compound F1) and theprimary arylamine (the compound G1), when the compound C1 and thecompound F1 are the same (X may be different), the compound A3 can beobtained with a higher yield, which is preferable. In addition, in thisreaction, when the Ullmann reaction described above is used, 2equivalent halogenated aryl can be reacted more efficiently with respectto the primary arylamine, which is preferable.

<Synthetic Method 4>

In this synthetic method, the following Compound M which is thetriarylamine derivative described in Embodiment 1 is synthesized by twoschemes, Reaction Scheme (A-6) and Reaction Scheme (A-7). ReactionScheme (A-6) shows a synthetic method of the above compound M in whichthe halogenated aryl (the compound C1) and secondary arylamine (acompound P3) are coupled to synthesize tertiary arylamine (a compoundP2); among three aryl groups of the tertiary arylamine (the compoundP2), the end groups of two aryl groups are halogenated to synthesizedihalide (a compound P1) of the tertiary arylamine; and after thatarylboronic acids and the compound P1 are coupled.

First, the tertiary arylamine (the compound P2) is synthesized bycoupling the halogenated aryl (the compound C1) and the secondaryarylamine (the compound P3). Note that here, the compound P2 is acompound in which both α and β in the compound M, which is thetriarylamine derivative described in Embodiment 1, are hydrogen. For thecoupling reaction, a coupling reaction using a metal catalyst can beused. As such a reaction, there are various reactions. As a typicalexample thereof; a Buchwald-Hartwig reaction, an Ullmann reaction, andthe like can be given. The detailed description on the reaction using aBuchwald-Hartwig reaction or an Ullmann reaction is made in SyntheticMethod 1-1, and this reaction can also be performed in a similar manner.Therefore, since the description on the synthetic method will berepeated, the description is omitted and the descriptions on aBuchwald-Hartwig reaction and Ullmann reaction in Synthetic Method 1-1are to be referred.

Subsequently, the dihalogenated aryl (the compound P1) is synthesized byhalogenating hydrogen of the compound P2, which corresponds to positionsof a and 3 in the compound M which is the triarylamine derivativedescribed in Embodiment 1. The halogenated reaction can be performedusing a halogenating agent. As the halogenating agent,N-Bromosuccinimide (abbreviation: NBS), N-Iodosuccinimide (abbreviation:NIS), bromine, iodine, potassium iodide, or the like can be used. As thehalogenating agent, the use of a bromide such as N-Bromosuccinimide(abbreviation: NBS) or bromine is preferable because synthesis can beperformed at low cost. Note that the halogenating agent is preferably 2equivalents or more, more preferably 2 equivalents in normality withrespect to the compound P2.

After that, the dihalogenated aryl (the compound P1) are coupled with anarylboronic acid having an aryl group represented by a and anarylboronic acid having an aryl group represented by β, so that thecompound M which is the triarylamine derivative described in Embodiment1 can be synthesized. In order to couple the arylboronic acids and thedihalogenated aryl (the compound P1), a reaction may be performed usinga metal catalyst in the presence of a base. As a reaction example, aSuzuki-Miyaura reaction can be given. In the case of performing thereaction by using a Suzuki-Miyaura reaction, the synthesis is performedin a manner similar to that of the synthesis described in SyntheticMethod 1-1. Since the description on the synthetic method will berepeated, the detailed description is omitted and the description on aSuzuki-Miyaura reaction in Synthetic Method 1-1 is to be referred. Notethat as the halogenating agent for the halogenation, it is preferable touse an iodide such as N-Iodosuccinimide (abbreviation: NIS), iodine, orpotassium iodide and select iodine as a halogen for substitution becausethis coupling reaction occurs efficiently in a shorter time. Inaddition, when the arylboronic acid having a group represented by a asan aryl group and the arylboronic acid having a group represented by Ras an aryl group are the same in this reaction, the compound M can beobtained with a high yield, which is preferable.

In Reaction Scheme (A-6), the halogenation of the tertiary arylamine(the compound P2) and the coupling with the arylboronic acid areperformed at the same time on two aryl groups; however, in ReactionScheme (A-7), a method is shown in which halogenation of the tertiaryarylamine (the compound P2) and coupling with an arylboronic acid areperformed on two aryl groups one by one.

First, one aryl group of the tertiary arylamine (the compound P2) ishalogenated using a halogenating agent to synthesize halogenated aryl (acompound Q3). As the halogenating agent, N-Bromosuccinimide(abbreviation: NBS), N-Iodosuccinimide (abbreviation: NIS), bromine,iodine, potassium iodide, or the like can be used. As the halogenatingagent, the use of a bromide such as N-Bromosuccinimide (abbreviation:NBS) or bromine is preferable because synthesis can be performed at lowcost. Note that the halogenating agent is preferably 1 equivalent innormality with respect to the compound P2 because a yield improves.

Subsequently, tertiary arylamine (a compound Q2) to which a or 3 (ca inReaction Scheme A-7) is introduced is synthesized by coupling thehalogenated aryl (the compound Q3) and an arylboronic acid having a or 3(a in Reaction Scheme A-7) as an aryl group. In order to couple thehalogenated aryl (the compound Q3) and the arylboronic acid, a reactionmay be performed using a metal catalyst in the presence of a base. As areaction example, a Suzuki-Miyaura reaction can be given. In the case ofperforming the reaction by using a Suzuki-Miyaura reaction, thesynthesis is performed in a manner similar to that of the synthesisdescribed in Synthetic Method 1-1. Since the description on thesynthetic method will be repeated, the detailed description is omittedand the description on a Suzuki-Miyaura reaction in Synthetic Method 1-1is to be referred. Note that as the halogenating agent for thehalogenation, it is preferable to use an iodide such asN-Iodosuccinimide (abbreviation: NIS), iodine, or potassium iodide andselect iodine as a halogen for substitution because this couplingreaction occurs efficiently in a shorter time.

After that, the compound Q2 which is the obtained tertiary arylamine ishalogenated to synthesize halogenated aryl (a compound Q1). Thehalogenation may be performed using a halogenation agent, and as thehalogenating agent, N-Bromosuccinimide (abbreviation: NBS),N-Iodosuccinimide (abbreviation: NIS), bromine, iodine, potassiumiodide, or the like can be used. As the halogenating agent, the use of abromide such as N-Bromosuccinimide (abbreviation: NBS) or bromine ispreferable because synthesis can be performed at low cost. Note that thehalogenating agent is preferably 1 equivalent in normality with respectto the compound Q2 because a yield improves.

Lastly, the halogenated aryl (the compound Q1) and an arylboronic acidhaving an aryl group represented by α or β (β in Reaction Scheme A-7)are coupled, so that the compound M, which is the triarylaminederivative described in Embodiment 1, to which α or β is introduced canbe synthesized. In order to couple the halogenated aryl (the compoundQ1) and the arylboronic acid, a reaction may be performed using a metalcatalyst in the presence of a base. As a reaction example, aSuzuki-Miyaura reaction can be given. In the case of performing thereaction by using a Suzuki-Miyaura reaction, the synthesis is performedin a manner similar to that of the synthesis described in SyntheticMethod 1-1. Since the description on the synthetic method will berepeated, the detailed description is omitted and the description on aSuzuki-Miyaura reaction in Synthetic Method 1-1 is to be referred. Notethat as the halogenating agent for the halogenation, it is preferable touse an iodide such as N-Iodosuccinimide (abbreviation: NIS), iodine, orpotassium iodide and select iodine as a halogen for substitution becausethis coupling reaction occurs efficiently in a shorter time.

<Synthetic Method 5>

In this synthetic method, the following compound M which is thetriarylamine derivative described in Embodiment 1 is synthesized byReaction Scheme (A-8). Reaction Scheme (A-8) shows a synthetic method ofthe above compound M in which primary arylamine (a compound R1) iscoupled at the same time with the halogenated aryl (the compound E1) inwhich α is bonded to its end group and the halogenated aryl (thecompound F1) in which β is bonded to its end group.

By this reaction, the compound M which is the triarylamine derivativedescribed in Embodiment 1 is synthesized in such a manner that thecompound R1 which is primary arylamine having an aryl group representedby Ar is coupled at the same time with the compound E1 which is thehalogenated aryl having an aryl group represented by α and the compoundF1 which is the halogenated aryl having a substituent represented by β,with the use of a metal catalyst. As such a reaction, there are variousreactions. As a typical example thereof; a Buchwald-Hartwig reaction, anUllmann reaction, and the like can be given. The detailed description onthe reaction using a Buchwald-Hartwig reaction or an Ullmann reaction ismade in Synthetic Method 1-1, and this reaction can also be performed ina similar manner. Therefore, since the description on the syntheticmethod will be repeated, the description is omitted and the descriptionson a Buchwald-Hartwig reaction and Ullmann reaction in Synthetic Method1-1 are to be referred. Note that in the method of coupling two kinds ofthe halogenated aryl (the compound E1 and the compound F1) and theprimary arylamine (the compound R1), when the compound E1 and thecompound F1 are the same (X may be different), the compound M can beobtained with a higher yield, which is preferable. In addition, in thisreaction, when the Ullmann reaction described above is used, 2equivalent halogenated aryl can be reacted more efficiently with respectto the primary arylamine, which is preferable.

Note that in each of Reaction Schemes (A-1) to (A-8), X represents ahalogen group, which is a chloro group, a bromo group, or an iodinegroup, preferably a bromo group or an iodine group. In addition, Ar is aphenyl group or a biphenyl group, a is a naphthyl group, and 3 ishydrogen or a naphthyl group. In addition, R¹ to R⁸ each independentlyrepresent any of hydrogen, an alkyl group having 1 to 6 carbon atoms, ora phenyl group; and n and m each independently represent 1 or 2.Although a number of reaction schemes are given as examples in the abovedescription, of course, the compound M which is the triarylaminederivative described in Embodiment 1 may be synthesized by any othersynthetic methods.

Embodiment 3

One embodiment of a light-emitting element using the triarylaminederivative described in Embodiment 1 will be shown below with referenceto FIG. 1A.

A light-emitting element of this embodiment has a plurality of layersbetween a pair of electrodes. In this embodiment, a light-emittingelement includes a first electrode 102, a second electrode 104, and anEL layer 103 provided between the first electrode 102 and the secondelectrode 104. In addition, in this embodiment, the first electrode 102functions as an anode and the second electrode 104 serves as a cathode.In other words, when voltage is applied to the first electrode 102 andthe second electrode 104 such that the potential of the first electrode102 is higher than that of the second electrode 104, light emission canbe obtained.

A substrate 101 is used as a support of the light-emitting element. Thesubstrate 101 can be formed with, for example, glass, plastic, or thelike. Note that materials other than glass or plastic can be used aslong as they can function as a support of the light-emitting element.

As the first electrode 102, a metal, an alloy, a conductive compound, amixture thereof, or the like having a high work function (specifically4.0 eV or more) is preferably used. Specifically, for example, indiumtin oxide (ITO), indium tin oxide containing silicon or silicon oxide,indium zinc oxide (IZO), indium oxide containing tungsten oxide and zincoxide (IWZO), and the like can be given. These conductive metal oxidefilms are generally formed by sputtering; however, the films may bemanufactured by applying a sol-gel method. For example, indium zincoxide (IZO) can be formed by a sputtering method using indium oxide intowhich zinc oxide of 1 wt % to 20 wt % is added, as a target. Indiumoxide containing tungsten oxide and zinc oxide (IWZO) can be formed by asputtering method using a target in which 0.5 wt % to 5 wt % of tungstenoxide and 0.1 wt % to 1 wt % of zinc oxide are mixed with indium oxide.In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W),chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu),palladium (Pd), a nitride of a metal material (such as titaniumnitride), and the like can be given.

There is no particular limitation on a stack structure of the EL layer103. The EL layer 103 may be formed as appropriate using a layerincluding the triarylamine derivative according to one embodiment of thepresent invention, which is described in Embodiment 1, in combinationwith any of a layer including a substance with a high electrontransporting property, a substance with a high hole transportingproperty, a layer including a substance with a high electron injectingproperty, a layer including a substance with a high hole injectingproperty, a layer including a substance with a bipolar property (amaterial with high electron and hole transporting properties), or thelike. For example, the EL layer 103 can be formed by an appropriatecombination of a hole injecting layer, a hole transporting layer, alight-emitting layer, an electron transporting layer, an electroninjecting layer, or the like. This embodiment will show the EL layer 103having a structure in which a hole injecting layer 111, a holetransporting layer 112, a light-emitting layer 113, and an electrontransporting layer 114 are sequentially stacked over the first electrode102. Specific materials to form each of the layers is given below.

The hole injecting layer 111 is a layer containing a substance having ahigh hole injecting property. As the substance with a high holeinjecting property, the following can be used: molybdenum oxide,vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, or thelike. Alternatively, the hole injecting layer 111 can be formed usingany of the following materials: phthalocyanine compounds such asphthalocyanine (HPC) and copper phthalocyanine (CuPc); aromatic aminecompounds such as4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB) and4,4′-bis(N-{4-[N-(3-methylphenyl)-N-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD); macromolecules such as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (abbreviation: PEDOT/PSS);and the like. Note that the triarylamine derivative described inEmbodiment 1 can also be used as the hole injecting material.

Alternatively, the hole injecting layer 111 can be formed using acomposite material in which an acceptor substance is contained in asubstance having a high hole transporting property. Note that by usingthe substance having a high hole transporting property containing anacceptor substance, a material used to form an electrode may be selectedregardless of its work function. In other words, besides a material witha high work function, a material with a low work function may also beused as the first electrode 102. As the acceptor substance,7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ), chloranil, and the like can be given. Further, transitionmetal oxides can be given. Further, oxides of metals that belong toGroup 4 to Group 8 of the periodic table can be given. Specifically,vanadium oxide, niobium oxide, tantalum oxide, chromium oxide,molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide areeach preferable because of a high electron accepting property. Amongthese, molybdenum oxide is especially preferable because it is stable inthe air and its hygroscopic property is low so that it can be easilytreated.

As the substance having a high hole transporting property used for thecomposite material, any of various compounds such as an aromatic aminecompound, a carbazole derivative, aromatic hydrocarbon, and amacromolecular compound (such as an oligomer, a dendrimer, and apolymer) can be used. The organic compound used for the compositematerial is preferably an organic compound having a high holetransporting property. Specifically, a substance having a hole mobilityof 10⁻⁶ cm²/Vs or more is preferably used. Note that any substance otherthan the above substances may also be used as long as it is a substancein which the hole transporting property is higher than the electrontransporting property. An organic compound which can be used as asubstance having a high hole transporting property for the compositematerial is specifically given below.

As aromatic amine compounds, for example, the following can be given:N,N′-di(p-tolyl)-N,N′-diphenyl-p-phenylenediamine (abbreviation:DTDPPA); 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl(abbreviation: DPAB);4,4′-bis(N-{4-[N-(3-methylphenyl)-N-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD);1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B); and the like.

As carbazole derivatives which can be used for the composite material,the following can be given:3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1);3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2);3-[N-(1-naphtyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1); and the like.

As other examples of carbazole derivatives which can be used for thecomposite material, the following can be given:4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP),1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB),9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA),1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, and thelike.

Further, as aromatic hydrocarbons which can be used for the compositematerial, for example, the following can be given:2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA);2-tert-butyl-9,10-di(1-naphthyl)anthracene,9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA);2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA);9,10-di(2-naphthyl)anthracene (abbreviation: DNA);9,10-diphenylanthracene (abbreviation: DPAnth); 2-tert-butylanthracene(abbreviation: t-BuAnth); 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA);2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene;9,10-bis[2-(1-naphthyl)phenyl]anthracene;2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene;2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene; 9,9′-bianthryl;10,10′-diphenyl-9,9′-bianthryl;10,10′-bis(2-phenylphenyl)-9,9′-bianthryl;10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl; anthracene;tetracene; rubrene; perylene; 2,5,8,11-tetra(tert-butyl)perylene; andthe like. Alternatively, pentacene, coronene, or the like can also beused. Note that it is preferable that the aromatic hydrocarbon have ahole mobility of 1×10⁻⁶ cm²/Vs or more, and in addition thereto, it ispreferable that the number of carbon atoms that forms a condensed ringbe 14 to 42 in terms of evaporativity at the time of evaporation or filmquality after film formation, when the above aromatic hydrocarbon isformed by an evaporation method.

Note that an aromatic hydrocarbon which can be used for the compositematerial may have a vinyl skeleton. As an aromatic hydrocarbon having avinyl group, for example, there are 4,4′-bis(2,2-diphenylvinyl)biphenyl(abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene(abbreviation: DPVPA), and the like.

Alternatively, a macromolecular compound such as poly(N-vinylcarbazole)(abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), orpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine (abbreviation:Poly-TPD) can be used.

Note that the triarylamine derivative described in Embodiment 1 can alsobe used as the organic compound in the composite material.

The hole transporting layer 112 is a layer containing a substance havinga high hole transporting property. In this embodiment, the triarylaminederivative described in Embodiment 1 is used as the hole transportinglayer.

In addition, the triarylamine derivative according to one embodiment ofthe present invention, which is described in Embodiment 1, can also beused for both the hole injecting layer 111 and the hole transportinglayer 112. In this case, an element can be manufactured easily and theuse efficiency of the material can be improved. Moreover, since energydiagrams of the hole injecting layer 111 and the hole transporting layer112 are the same or similar, carriers can be transported easily betweenthe hole injecting layer 111 and the hole transporting layer 112.

The light-emitting layer 113 is a layer containing a light-emittingsubstance. The light-emitting layer 113 may be formed using a filmincluding only a light-emitting substance or a film in which alight-emitting substance is dispersed in a host material.

Materials that can be used as the above light-emitting substance in thelight-emitting layer 113 are not particularly limited, and light emittedby these materials may be fluorescence or phosphoresce. For example, thefollowing materials can be given as the above light-emitting substance.

As a fluorescent light-emitting material, the following materials havingan emission wavelength of 450 nm or more can be given in addition toN,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA), and the like:4-(9H-carbazol-9-yl)-4′-(9,10-diphenyl-2-anthryl)triphenylamine(abbreviation: 2YGAPPA);N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA); perylene; 2,5,8,11-tetra-tert-butylperylene(abbreviation: TBP);4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA);N,N′-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N′,N′-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA);N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: 2PCAPPA);N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPPA);N,N,N′,N′,N″,N″,N′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetramine(abbreviation: DBC1); coumarin 30;N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA);N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA);N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA);N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA);9,10-bis(1,1′-biphenyl-2-yl)]-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA); N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA); coumarin 545T; N,N′-diphenylquinacridone(abbreviation: DPQd); rubrene;5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT);2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation:DCM1);2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[i]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCM2);N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD);7,13-diphenyl-N,N,N,N-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD);2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTI);2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTB); 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile(abbreviation: BisDCM);2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: BisDCJTM); and the like.

As a phosphorescent light-emitting material, in addition tobis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)tetrakis(1-pyrazolyl)borate(abbreviation: FIr6), materials having an emission wavelength in therange of 470 nm to 500 nm, such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(II)picolinate(abbreviation: FIrpic);bis[2-(3′,5′-bistrifluoromethylphenyl)pyridinato-N,C^(2′)]iridium(III)picolinate (abbreviation: Ir(CF₃ppy)₂(pic)); andbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)acetylacetonate(abbreviation: FIracac) can be given, and materials having an emission(green light emission) wavelength of 500 nm or more can be given, suchas tris(2-phenylpyridinato)iridium(III) (abbreviation: Ir(ppy)₃);bis(2-phenylpyridinato)iridium(III) acetylacetonate (abbreviation:Ir(ppy)₂(acac)); tris(acetylacetonato)(monophenanthroline)terbium (Ill)(abbreviation: Tb(acac)₃(Phen));bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation:Ir(bzq)₂(acac));bis(2,4-diphenyl-1,3-oxazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(dpo)₂(acac));bis[2-(4′-perfluorophenylphenyl)pyridinato]iridium(Ill)acetylacetonate(abbreviation: Ir(p-PF-ph)₂(acac));bis(2-phenylbenzothiazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(bt)₂(acac));bis[2-(2′-benzo[4,5-a]thienyl)pyridinato-N,C^(3′)]iridium(III)acetylacetonate (abbreviation: Ir(btp)₂(acac));bis(1-phenylisoquinolinato-N,C^(2′))iridium(II) acetylacetonate(abbreviation: Ir(piq)₂(acac));(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: Ir(Fdpq)₂(acac));(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: Ir(tppr)₂(acac));2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II)(abbreviation: PtOEP);tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III)(abbreviation: Eu(DBM)₃(Phen)); andtris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(Ill) (abbreviation: Eu(TTA)₃(Phen)).

Having a large energy gap or triplet energy, the triarylamine derivativedescribed in Embodiment 1 can be very preferably used as a material thatforms the hole transporting layer in contact with the light-emittinglayer. Among the materials described above, when the fluorescentlight-emitting substance having an emission (blue light emission)wavelength of 450 nm or more or the phosphorescent light-emittingsubstance having an emission (green light emission) wavelength of 470 nmor more, preferably 500 nm or more is used, reduction in luminousefficiency or color purity unlikely occurs, which is a preferablestructure.

In addition, materials that can be used as the above host material arenot particularly limited and metal complexes, heterocyclic compounds,and aromatic amine compounds can be given, for example. As metalcomplexes, the following can be given:tris(8-quinolinolato)aluminum(III) (abbreviation: Alq);tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviatior: Almq₃);bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂);bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq); bis(8-quinolinolato)zinc(II) (abbreviation: Znq);bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO);bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); andthe like. As heterocyclic compounds, the following can be given:2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD); 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7);3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ);2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI); bathophenanthroline (abbreviation: BPhen);bathocuproine (abbreviation: BCP);9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation:CO11); and the like. As aromatic amine compounds, the following can begiven: 4,4′-bis[N-(l-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPBor α-NPD);N,N′-bis(3-methylphenyl)-N,N-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD);4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]-1,1′-biphenyl(abbreviation: BSPB); and the like. Moreover, condensed polycyclicaromatic compounds such as an anthracene derivative, a phenanthrenederivative, a pyrene derivative, a chrysene derivative, and adibenzo[g,p]chrysene derivative can be given. The following isspecifically given as the condensed polycyclic aromatic compound:9,10-diphenylanthracene (abbreviation: DPAnth);N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: CzA1PA); 4-(10-phenyl-9-anthryl)triphenylamine(abbreviation: DPhPA);4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA); N,9-diphenyl-N-[4-(l0-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA);N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine(abbreviation: PCAPBA);N,9-diphenyl-N-(9,10-diphenyl-2-anthryl)-9H-carbazol-3-amine(abbreviation: 2PCAPA); 6,12-dimethoxy-5,11-diphenylchrysene;N,N,N′,N′,N″,N″,NP′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetramine(abbreviation: DBC1); 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPA);3,6-diphenyl-9-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazole(abbreviation: DPCzPA); 9,10-bis(3,5-diphenylphenyl)anthracene(abbreviation: DPPA); 9,10-di(2-naphthyl)anthracene (abbreviation: DNA);2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA);9,9′-bianthryl (abbreviation: BANT);9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation: DPNS);9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2);3,3′,3″-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3); and thelike. From these materials and known materials, a substance having anenergy gap larger than that of the light-emitting substance may beselected. Moreover, in the case where a light-emitting substance emitsphosphorescence, a substance having a triplet energy (energy differencebetween a ground state and a triplet excitation state) which is higherthan that of the light-emitting substance may be selected as a hostmaterial.

The light-emitting layer 113 may be a stack of two or more layers. Forexample, in the case where the light-emitting layer 113 is formed bystacking a first light-emitting layer and a second light-emitting layerin that order from the hole transporting layer side, for example, thefirst light-emitting layer can be formed using a substance having a holetransporting property as the host material and the second light-emittinglayer can be formed using a substance having an electron transportingproperty as the host material.

When the light-emitting layer having the structure described above isformed using a plurality of materials, the light-emitting layer can beformed using co-evaporation by a vacuum evaporation method; or anink-jet method, a spin coating method, a dip coating method, or the likeas a method for mixing a solution.

The electron transporting layer 114 is a layer containing a substancehaving a high electron transporting property. For example, the electrontransporting layer 114 is a layer including a metal complex having aquinoline skeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviation: BeBq₂), orbis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation:BAlq). Alternatively, a metal complex having an oxazole-based orthiazole-based ligand, such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(abbreviation: Zn(BOX)₂) or bis[2-(2-hydroxyphenyl)-benzothiazolato]zinc(abbreviation: Zn(BTZ)₂) can be used. Besides the metal complexes,2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen),bathocuproine (abbreviation: BCP), or the like can also be used. Thesubstances described here are mainly substances having an electronmobility of 10⁻⁶ cm²/Vs or more. Note that a substance other than theabove substances may be used as long as it has a higher electrontransporting property than a hole transporting property.

Further, the electron transporting layer is not limited to a singlelayer, and two or more layers made of the above substances may bestacked.

Further, a layer for controlling transport of electron carriers may beprovided between the electron transporting layer and the light-emittinglayer. Specifically, the layer for controlling transport of electroncarriers is a layer formed by adding a small amount of substance havinga high electron trapping property to the material having a high electrontransporting property as described above, so that carrier balance can beadjusted. Such a structure is very effective in suppressing a problem(such as shortening of element lifetime) caused when electrons passthrough the light-emitting layer.

In addition, an electron injecting layer may be provided between theelectron transporting layer and the second electrode 104, in contactwith the second electrode 104. As the electron injecting layer, analkali metal, an alkaline earth metal, or a compound thereof such aslithium fluoride (LiF), cesium fluoride (CsF), or calcium fluoride(CaF₂) can be used. For example, a layer of a material having anelectron transporting property containing an alkali metal, an alkalineearth metal, or a compound thereof, specifically a layer of Alqcontaining magnesium (Mg), can be used. By using a layer of a substancehaving an electron transporting property containing an alkali metal oran alkaline earth metal as the electron injecting layer, electroninjection from the second electrode 104 is performed efficiently, whichis preferable.

As a substance for forming the second electrode 104, a metal, an alloy,an electrically conductive compound, a mixture thereof, or the likehaving a low work function (specifically 3.8 eV or less) can be used. Asa specific example of such a cathode material, an element belonging togroup 1 or 2 in the periodic table, that is, an alkali metal such aslithium (Li) or cesium (Cs); an alkaline earth metal such as magnesium(Mg), calcium (Ca), or strontium (Sr); an alloy containing the elementbelonging to group 1 or 2 (MgAg or AILi); a rare-earth metal such aseuropium (Eu) or ytterbium (Yb); an alloy thereof; or the like can beused. However, when the electron injecting layer is provided between thesecond electrode 104 and the electron transporting layer, the secondelectrode 104 can be formed from any of a variety of conductivematerials such as Al, Ag, ITO, or indium oxide-tin oxide includingsilicon or silicon oxide regardless of its work function. Theseconductive materials can be formed by a sputtering method, an ink-jetmethod, a spin coating method, or the like.

Various methods can be used for forming the EL layer 103, regardless ofa dry method or a wet method. For example, a vacuum evaporation method,an ink-jet method, a spin coating method, or the like may be used. Inaddition, different film formation methods may be used for forming therespective electrodes or layers. In addition, when a film is formedusing the triarylamine derivative described in Embodiment 1 by a vacuumevaporation method or when the above triarylamine derivative is purifiedby a sublimation purification method, it is preferable to select atriarylamine derivative having molecular weight of 1000 or less,preferably 800 or less, for the triarylamine derivative in order toavoid influence on the triarylamine derivative due to heat In addition,in order to improve solubility in a solvent in the case of using a wetmethod, it is preferable to use a triarylamine derivative described inEmbodiment 1, in which an alkyl group is introduced as a substituent.

Similarly, the electrodes may be formed by a wet process such as asol-gel process or by a wet process using a metal paste. Further, theelectrode may be formed by a dry method such as a sputtering method or avacuum evaporation method.

In the light-emitting element according to one embodiment of the presentinvention having the structure as described above, the potentialdifference generated between the first electrode 102 and the secondelectrode 104 makes a current flow, whereby holes and electrons arerecombined in the light-emitting layer 113 that is a layer containinghigh light-emitting property and thus light is emitted. That is, thelight-emitting element of the present invention has a structure in whicha light-emitting region is formed in the light-emitting layer 113.

The light emission is extracted out through one of or both the firstelectrode 102 and the second electrode 104. Therefore, one of or boththe first electrode 102 and the second electrode 104 is/are formed usingan electrode having a light transmitting property. In the case whereonly the first electrode 102 has a light transmitting property, lightemission is extracted from a substrate side through the first electrode102. Alternatively, when only the second electrode 104 has alight-transmitting property, light emission is extracted from the sideopposite to the substrate through the second electrode 104. When each ofthe first electrode 102 and the second electrode 104 has alight-transmitting property, light emission is extracted from both thesubstrate side and the side opposite to the substrate side through thefirst electrode 102 and the second electrode 104.

The structure of the layers provided between the first electrode 102 andthe second electrode 104 is not limited to the above one. However, it ispreferable to use a structure in which a light-emitting region whereholes and electrons are recombined is provided away from the firstelectrode 102 and the second electrode 104 so as to prevent quenchingdue to the proximity of the light-emitting region and a metal used forthe electrode or the carrier (electron or hole) injecting layer. Theorder of stacking the layers is not limited to the above, and thefollowing order, which is opposite to the layers in FIG. 1A, may beemployed: the second electrode, the electron injecting layer, theelectron transporting layer, the light-emitting layer, the holetransporting layer, the hole injecting layer, and the first electrodefrom the substrate side.

In addition, as for the hole transporting layer or the electrontransporting layer in direct contact with the light-emitting layer,particularly a carrier (electron or hole) transporting layer in contactwith a side closer to a light-emitting region in the light-emittinglayer 113, in order to suppress energy transfer from an exciton which isgenerated in the light-emitting layer, it is preferable that an energygap thereof be larger than an energy gap of a light-emitting substancewhich forms the light-emitting layer or an energy gap of alight-emitting substance included in the light-emitting layer.

Since, the triarylamine derivative described in the Embodiment 1, whichhas a large energy gap, is used as the hole transporting layer in thelight-emitting element of this embodiment, light emission havingfavorable color purity can be obtained efficiently even when thelight-emitting substance having a large energy gap that emits blue lightis used. Accordingly, a light-emitting element having lower powerconsumption can be provided. Specifically, since the energy gap of thetriarylamine derivative described in Embodiment 1 is about 3.0 eV to 3.4eV, the triarylamine derivative can be preferably used without reductionin luminous efficiency or color purity due to energy transfer in thelight-emitting element having a light-emitting layer where alight-emitting substance having an energy gap of less than or equal tothe above energy gap is used. Note that the energy gap of a substancethat emits blue light is about 2.7 eV to 3.0 eV.

In this embodiment, the light-emitting element is manufactured over asubstrate made of glass, plastic, or the like. By forming a plurality ofsuch light-emitting elements over a substrate, a passive matrixlight-emitting device can be manufactured. In addition, for example, athin film transistor (TFT) may be formed over a substrate made of glass,plastic, or the like, and a light-emitting element may be manufacturedover an electrode electrically connected to the TFT. Accordingly, anactive matrix light-emitting device which controls the driving of alight-emitting element by a TFT can be manufactured. Note that astructure of the TFT is not particularly limited. Either a staggered TFTor an inverted staggered TFT may be employed. In addition, crystallinityof a semiconductor used for the TFT is also not particularly limited,and an amorphous semiconductor or a crystalline semiconductor may beused. In addition, a driving circuit formed over a TFT substrate may beformed using an n-type TFT and a p-type TFT or any one of an n-type TFTor a p-type TFT.

The triarylamine derivative according to one embodiment of the presentinvention has a large energy gap; therefore, when the above triarylaminederivative is used as a light-emitting substance, a light-emittingelement with sufficiently short wavelengths and high color purity forblue light emission can be obtained.

Embodiment 4

In this embodiment, a light-emitting element having a differentstructure from that shown in Embodiment 3 will be described.

A structure is described in which light emission is obtained from asubstance having a light-emitting property by forming the light-emittinglayer 113 described in Embodiment 3 in such a manner that the substancehaving a light-emitting property is dispersed into the triarylaminederivative described in Embodiment 1; that is, a structure in which thetriarylamine derivative described in Embodiment 1 is used as the hostmaterial of the light-emitting layer 113.

Since the triarylamine derivative described in Embodiment 1 has a largeenergy gap, it can effectively excite other light-emitting substances toachieve light emission; therefore, the triarylamine derivative describedin Embodiment 1 can be preferably used as the host material and lightemission resulted from the light-emitting substance can be obtained.Therefore, a light-emitting element having high luminous efficiency withsmall energy loss can be obtained. In addition, a light-emitting elementwhich can easily provide light emission of a desired color that isderived from the light-emitting substance can be formed. Accordingly, alight-emitting element which emits light with high color purity can beeasily obtained.

Here, there is no particular limitation on a light-emitting substancedispersed into the triarylamine derivative described in Embodiment 1,and various materials can be used.

Specifically, as a fluorescent light-emitting material, the followingmaterials having an emission wavelength of 450 nm or more can be givenin addition toN,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA), and the like:4-(9H-carbazol-9-yl)-4′-(9,10-diphenyl-2-anthryl)triphenylamine(abbreviation: 2YGAPPA);N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA); perylene; 2,5,8,11-tetra-tert-butylperylene(abbreviation: TBP);4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA);N,N″-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N′,N′-triphenyl-1,4-phenylenediamine](abbreviation: DPABPA);N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: 2PCAPPA);N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPPA);N,N,N′,N′,N″,N″,N′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetramine(abbreviation: DBC1); coumarin 30;N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA);N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA);N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA);N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA);9,10-bis(1,1′-biphenyl-2-yl)]-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA); N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA); coumarin 545T; N,N′-diphenylquinacridone(abbreviation: DPQd); rubrene;5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT);2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile(abbreviation: DCM1);2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCM2);N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD);7,13-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD);2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTI);2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[j]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTB); 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile(abbreviation: BisDCM);2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[y]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: BisDCJTM); and the like.

As a phosphorescent light-emitting material, in addition tobis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)tetrakis(1-pyrazolyl)borate(abbreviation: FIr6), materials having an emission wavelength in therange of 470 nm to 500 nm, such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C]iridium(Ill)picolinate(abbreviation: FIrpic);bis[2-(3′,5′-bistrifluoromethylphenyl)pyridinato-N,C^(2′)]iridium(III)picolinate (abbreviation: Ir(CF₃ppy)₂(pic)); andbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)acetylacetonate(abbreviation: FIracac) can be given, and materials having an emission(green light emission) wavelength of 500 nm or more can be given, suchas tris(2-phenylpyridinato)iridium(III) (abbreviation: Ir(ppy)₃);bis(2-phenylpyridinato)iridium(III) acetylacetonate (abbreviation:Ir(ppy)₂(acac)); tris(acetylacetonato)(monophenanthroline)terbium (III)(abbreviation: Tb(acac)₃(Phen));bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation:Ir(bzq)₂(acac));bis(2,4-diphenyl-1,3-oxazolato-N,C^(2′))iridium(II)acetylacetonate(abbreviation: Ir(dpo)₂(acac));bis[2-(4′-perfluorophenylphenyl)pyridinato]iridium(III)acetylacetonate(abbreviation: Ir(p-PF-ph)₂(acac));bis(2-phenylbenzothiazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(bt)₂(acac));bis[2-(2′-benzo[4,5-a]thienyl)pyridinato-N,C^(3′)]iridium(III)acetylacetonate (abbreviation: Ir(btp)₂(acac));bis(1-phenylisoquinolinato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(piq)₂(acac));(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: Ir(Fdpq)₂(acac));(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: Ir(tppr)₂(acac));2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(l)(abbreviation: PtOEP); tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: Eu(DBM)₃(Phen)); andtris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium (III) (abbreviation: Eu(TTA)₃(Phen)).

Among the materials described above, when the fluorescent light-emittingsubstance having an emission wavelength of 450 nm or more or thephosphorescent light-emitting substance having an emission wavelength of470 nm or more, preferably 470 nm or more and more preferably 500 nm ormore, is used as the light-emitting substance, reduction in luminousefficiency or color purity unlikely occurs, and thus a light-emittingelement having preferable luminous efficiency with high color purity canbe obtained. Accordingly, a light-emitting element having lower powerconsumption can be provided. Further, other organic compounds may bedispersed at the same time in addition to the triarylamine derivativedescribed in Embodiment 1 and the light-emitting substance dispersedinto the triarylamine derivative. In this case, a substance thatimproves carrier balance of the light-emitting layer is preferable andthe above substance having a high electron transporting property and thelike are given, and a substance that has an energy gap as wide as thetriarylamine derivative according to one embodiment of the presentinvention is preferable.

Note that other than the light-emitting layer 113, the structuredescribed in Embodiment 3 can be used as appropriate; however, as thehole transporting layer 112, other than the materials shown inEmbodiment 3, a substance having a high hole transporting property suchas the following aromatic amine compounds can be used4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB);N,N-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD); 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(abbreviation: TDATA);4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA);4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]-1,1′-biphenyl(abbreviation: BSPB); and the like. The substances described here aremainly substances having an electron mobility of 10⁻⁶ cm²/Vs or more.Note that a substance other than the above substances may be used aslong as it has a higher hole transporting property than an electrontransporting property. Note that the layer containing a substance havinga high hole transporting property is not limited to a single layer, andtwo or more layers made of the above substances may be stacked.

Further, a macromolecular compound such as poly(N-vinylcarbazole)(abbreviation: PVK) or poly(4-vinyltriphenylamine) (abbreviation: PVTPA)can also be used for the hole transporting layer 112.

Embodiment 5

In this embodiment, an embodiment of a light-emitting element with astructure in which a plurality of light-emitting units are stacked(hereinafter this type of light-emitting element is also referred to asa stacked element) is described with reference to FIG. 1B. Thislight-emitting element is a light-emitting element having a plurality oflight-emitting units between a first electrode and a second electrode.The light-emitting units can be similar to the EL layer 103 described inEmbodiments 3 or 4. That is, Embodiment 3 or 4 describes thelight-emitting element having a single light-emitting unit, and thisembodiment describes a light-emitting element having a plurality oflight-emitting units.

In FIG. 1B, a first light-emitting unit 511 and a second light-emittingunit 512 are stacked between a first electrode 501 and a secondelectrode 502, and a charge generation layer 513 is provided between thefirst light-emitting unit 511 and the second light-emitting unit 512.The first electrode 501 and the second electrode 502 correspond to thefirst electrode 102 and the second electrode 104 in Embodiment 3,respectively, and electrodes similar to those described in Embodiment 3can be used as the first electrode 501 and the second electrode 502.Further, the first light-emitting unit 511 and the second light-emittingunit 512 may have the same structure or different structures.

The charge generation layer 513 includes a composite material of anorganic compound and a metal oxide. This composite material of anorganic compound and a metal oxide is the composite material describedin Embodiment 3 and includes an organic compound and a metal oxide suchas vanadium oxide, molybdenum oxide, or tungsten oxide. As the organiccompound, any of various compounds such as an aromatic amine compound, acarbazole derivative, aromatic hydrocarbon, and a macromolecularcompound (such as an oligomer, a dendrimer, and a polymer) can be used.Note that the organic compound having a hole mobility of 10⁻⁶ cm²/Vs ormore is preferably used as a hole transporting organic compound. Notethat any substance other than the above substances may also be used aslong as it is a substance in which the hole transporting property ishigher than the electron transporting property. The composite of anorganic compound and a metal oxide is superior in a carrier injectingproperty and a carrier transporting property, and accordingly,low-voltage driving and low-current driving can be realized.

Alternatively, the charge generation layer 513 may be formed with acombination of a layer containing the composite material of an organiccompound and a metal oxide with a layer formed using another material.For example, the charge generation layer 513 may be formed with acombination of a layer containing the composite material of an organiccompound and a metal oxide and a layer including one compound selectedfrom electron donating substances and a compound having a high electrontransporting property. Further, the charge generation layer 513 may beformed with a combination of a layer containing the composite materialof an organic compound and a metal oxide with a transparent conductivefilm.

In any case, the charge generation layer 513 which is interposed betweenthe first light-emitting unit 511 and the second light-emitting unit 512is acceptable as long as electrons are injected to one light-emittingunit and holes are injected to the other light-emitting unit when avoltage is applied between the first electrode 501 and the secondelectrode 502. For example, in FIG. 1B, any layer can be employed as thecharge generation layer 513 as long as the layer injects electrons intothe first light-emitting unit 511 and holes into the secondlight-emitting unit 512 when voltage is applied so that the potential ofthe first electrode is higher than that of the second electrode.

Although the light-emitting element having two light-emitting units isdescribed in this embodiment, a light-emitting element in which three ormore light-emitting units are stacked can be employed in a similarmanner. When the charge generation layer is provided between the pair ofelectrodes so as to partition the plural light-emitting units like thelight-emitting element according to this embodiment, the element canhave long lifetime in a high luminous region while keeping low currentdensity. In the case where the light-emitting element is applied tolighting as an application example, voltage drop due to resistance of anelectrode material can be reduced. Accordingly, light can be uniformlyemitted with a large area. Moreover, a light-emitting device with lowpower consumption, which can be driven at low voltage, can be achieved.

The light-emitting units emit light having different colors from eachother, thereby obtaining light emission of a desired color in the wholelight-emitting element. For example, in the light-emitting elementhaving two light-emitting units, when the emission color of the firstlight-emitting unit and the emission color of the second light-emittingunit are complementary colors, a light-emitting element which emitswhite light as a whole can be obtained. Note that “complementary color”means a relation between colors which becomes an achromatic color whenthey are mixed. That is, white light emission can be obtained by mixtureof lights obtained from substances emitting the lights of complementarycolors. The same can be applied to a light-emitting element having threelight-emitting units. For example, when the first light-emitting unitemits red light, the second light-emitting unit emits green light, andthe third light-emitting unit emits blue light, white light can beemitted from the whole light-emitting element.

Since the light-emitting element of this embodiment includes thetriarylamine derivative described in Embodiment 1, a light-emittingelement having preferable luminous efficiency can be obtained. Inaddition, since the light-emitting units which include the triarylaminederivative can obtain light that is derived from a light-emittingsubstance with favorable color purity, color of a light-emitting elementas a whole is easily adjusted.

Note that this embodiment can be combined with any of other embodimentsas appropriate.

Embodiment 6

This embodiment shows an example in which the triarylamine derivativedescribed in Embodiment 1 is used for an active layer of a verticaltransistor (SIT), which is a kind of organic semiconductor element.

The element has a structure in which a thin-film active layer 1202including a triarylamine derivative described in Embodiment 1 isinterposed between a source electrode 1201 and a drain electrode 1203,and a gate electrode 1204 is embedded in the active layer 1202, asillustrated in FIG. 2. The gate electrode 1204 is electrically connectedto a unit for applying a gate voltage, and the source electrode 1201 andthe drain electrode 1203 are electrically connected to a unit forcontrolling a source-drain voltage.

In such an element structure, when a voltage is applied between thesource and the drain under the condition where a gate voltage is notapplied, a current flows (becomes an ON state). When a gate voltage isapplied in this state, a depletion layer is generated in the peripheryof the gate electrode 1204, whereby a current does not flow (becomes anOFF state). With the above mechanism, the element operates as atransistor.

In a vertical transistor, a material which has both a carriertransporting property and favorable film quality is required for anactive layer like in a light-emitting element. The triarylaminederivative described in Embodiment 1 is useful because it sufficientlymeets these requirements.

Embodiment 7

In this embodiment, a light-emitting device manufactured using thetriarylamine derivative described in Embodiment 1 will be described.

In this embodiment, a light-emitting device manufactured using thetriarylamine derivative described in Embodiment 1 is described withreference to FIGS. 3A and 3B. FIG. 3A is a top view of thelight-emitting device, and FIG. 3B is a cross-sectional view taken alongA-A′ and B-B′ of FIG. 3A. This light-emitting device includes a drivercircuit portion (source-side driver circuit) 601, a pixel portion 602,and a driver circuit portion (gate-side driver circuit) 603, which areindicated by dotted lines, in order to control the light emission of alight-emitting element. Moreover, reference numeral 604 denotes asealing substrate; 605, a sealant; and 607, a space surrounded by thesealant 605.

A lead wiring 608 transmits a signal to be inputted to the source-sidedriver circuit 601 and the gate-side driver circuit 603 and receives avideo signal, a clock signal, a start signal, a reset signal, or thelike from an FPC (Flexible Printed Circuit) 609 which is an externalinput terminal Although only the FPC is illustrated here, this FPC maybe provided with a printed wiring board (PWB). The light-emitting devicein this specification includes not only a light-emitting device body butalso the light-emitting device in which an FPC or a PWB is attachedthereto.

Next, a cross-sectional structure is described with reference to FIG.3B. Although the driver circuit portion and the pixel portion are formedover an element substrate 610, the source-side driver circuit 601 whichis the driver circuit portion and one pixel in the pixel portion 602 areillustrated here.

Note that a CMOS circuit in which an n-channel TFT 623 and a p-channelTFT 624 are combined is formed as the source-side driver circuit 601.The driver circuit may be formed by various CMOS circuits, PMOScircuits, or NMOS circuits. It is not always necessary to form thedriver circuit on the substrate integrally as in this embodiment, and itis also possible to form the driver circuit not on the substrate butoutside the substrate externally.

The pixel portion 602 has a plurality of pixels, each of which includesa switching TFT 611, a current control TFT 612, and a first electrode613 which is electrically connected to a drain of the current controlTFT 612. Note that an insulator 614 is formed to cover an end portion ofthe first electrode 613. Here, the insulator 614 is formed using apositive photosensitive-acrylic resin film.

In order to improve the coverage, the insulator 614 is provided suchthat either an upper edge portion or a lower edge portion of theinsulator has a curved surface with a curvature. For example, in thecase of using a positive photosensitive-acrylic as a material for theinsulator 614, it is preferable to give only the upper edge portion ofthe insulator 614 a curved surface, having a curvature radius (of 0.2 μmto 3 μm). As the insulator 614, either a negative type which becomesinsoluble in etchant by irradiation with light or a positive type whichbecomes soluble in etchant by irradiation with light can be used.

An EL layer 616 and a second electrode 617 are formed over the firstelectrode 613. Here, a material having a high work function ispreferably used as a material for the first electrode 613 which servesas an anode. For example, a single-layer film of an ITO film, an indiumtin oxide film containing silicon, an indium oxide film containing 2 wt% to 20 wt % of zinc oxide, a titanium nitride film, a chromium film, atungsten film, a Zn film, a Pt film, or the like can be used. Besidesthese single-layer films, a stack of a titanium nitride film and a filmcontaining aluminum as its main component; a stack of three layers of atitanium nitride film, a film containing aluminum as its main component,and a titanium nitride film; or the like can be used. Note that when astacked structure is employed, resistance of a wiring is low, and afavorable ohmic contact is obtained.

The EL layer 616 is formed by various methods such as an evaporationmethod using an evaporation mask, an ink-jet method, or a spin coatingmethod. The EL layer 616 contains the triarylamine derivative describedin Embodiment 1. Further, the EL layer 616 may also be formed usinganother material including a low molecular compound or a macromolecularcompound (including an oligomer or a dendrimer).

As a material used for the second electrode 617, which is formed overthe EL layer 616 and serves as a cathode, a material having a low workfunction (Al, Mg, Li, Ca, or an alloy or a compound thereof such asMgAg, MgIn, AILi, LiF, or CaF₂) is preferably used. In the case wherelight generated in the EL layer 616 passes through the second electrode617, the second electrode 617 is preferably formed using a stack of athin metal film with a reduced thickness and a transparent conductivefilm (ITO, indium oxide containing 2 wt % to 20 wt % of zinc oxide,indium tin oxide containing silicon, zinc oxide (ZnO), or the like).

In addition, a light-emitting element 618 includes the first electrode613, the EL layer 616, and the second electrode 617. The light-emittingelement 618 has any of the structures described in Embodiments 3 to 5.Further, the pixel portion, which includes a plurality of light-emittingelements, in the light-emitting device of this embodiment may includeboth the light-emitting element with any of the structures described inEmbodiments 3 to 5 and the light-emitting element with a structure otherthan those.

When the sealing substrate 604 and the element substrate 610 areattached to each other with the sealant 605, the light-emitting element618 is provided in the space 607 surrounded by the element substrate610, the sealing substrate 604, and the sealant 605. There are alsocases where the space 607 is filled with an inert gas (such as nitrogenor argon) as such a filler, or where the space 607 is filled with thesealant 605.

As the sealant 605, an epoxy resin is preferably used. In addition, itis preferable to use a material that allows permeation of moisture oroxygen as little as possible. As the sealing substrate 604, a plasticsubstrate formed of FRP (Fiberglass-Reinforced Plastics), PVF (polyvinylfluoride), polyester, acrylic, or the like can be used besides a glasssubstrate or a quartz substrate.

As described above, the light-emitting device manufactured using thetriarylamine derivative described in Embodiment 1 can be obtained.

Since the triarylamine derivative described in Embodiment 1 is used forthe light-emitting device according to one embodiment of the presentinvention, preferable characteristics can be obtained. Specifically,since the triarylamine derivative described in Embodiment 1 has a largeenergy gap and can suppress energy transfer from a light-emittingsubstance, a light-emitting element having preferable luminousefficiency can be provided and thus a light-emitting device whichconsumes less power can be obtained according to one embodiment of thepresent invention. In addition, since light emission having high colorpurity, especially preferable blue light emission can also be obtained,a light-emitting device having excellent color reproducibility and highdisplay quality can be obtained.

Although an active matrix light-emitting device is described in thisembodiment as described above, a passive matrix light-emitting devicemay be alternatively manufactured. FIGS. 4A and 4B illustrate a passivematrix light-emitting device manufactured by applying one embodiment ofthe present invention. FIG. 4A is a perspective view of thelight-emitting device, and FIG. 4B is a cross-sectional view taken alongX-Y of FIG. 4A. In FIGS. 4A and 4B, an EL layer 955 is provided over asubstrate 951 and between an electrode 952 and an electrode 956. Theedge of the electrode 952 is covered with an insulating layer 953. Apartition wall layer 954 is provided on the insulating layer 953.Sidewalls of the partition wall layer 954 have a slant such that adistance between one sidewall and the other sidewall becomes shorter asthe sidewalls gets closer to the substrate surface. That is, a crosssection in the direction of a narrow side of the partition wall layer954 has a trapezoidal shape, and a lower base (a side facing a similardirection as a surface direction of the insulating layer 953, and is incontact with the insulating layer 953) is shorter than an upper base (aside facing a similar direction as the surface direction of theinsulating layer 953, and is not in contact with the insulating layer953). By providing the partition wall layer 954 in this manner, defectsof the light-emitting element due to static charge and the like can beprevented. The passive matrix light-emitting device can also be drivenwith low power consumption when it includes the light-emitting elementaccording to one embodiment of the present invention, which operates ata low driving voltage.

Embodiment 8

In this embodiment, an electronic device according to one embodiment ofthe present invention including the light-emitting device described inEmbodiment 7 in part thereof will be described. The electronic deviceaccording to one embodiment of the present invention includes thetriarylamine derivative described in Embodiment 1 and thus an electronicdevice having a display portion which consumes less power can beobtained. In addition, an electronic device having a display portionwith excellent color reproducibility and high display quality can beobtained.

Examples of electronic devices each having a light-emitting elementformed using the triarylamine derivative described in Embodiment 1include a camera such as a video camera or a digital camera, a goggletype display, a navigation system, an audio playback device (e.g., a caraudio component, an audio component, and the like), a computer, a gamemachine, a portable information terminal (e.g., a mobile computer, acellular phone, a portable game machine, an electronic book, and thelike), an image reproducing device provided with recording media(specifically, a device capable of reproducing recording media such asdigital versatile discs (DVDs) and provided with a display device thatcan display the image), and the like. Such electronic devices areillustrated in FIGS. 5A to 5D.

FIG. 5A illustrates a television device according to one embodiment ofthe present invention, which includes a housing 9101, a supporting base9102, a display portion 9103, speaker portions 9104, a video inputterminal 9105, and the like. In the display portion 9103 of thistelevision device, light-emitting elements similar to those described inany of Embodiments 3 to 5 are arranged in matrix. The luminousefficiency of the light-emitting elements is high. The light-emittingelements are capable of emitting light of favorable colors. Therefore,this television device having the display portion 9103 which is formedusing the light-emitting elements consumes less power. In addition, thetelevision device can have excellent color reproducibility and highdisplay quality.

FIG. 5B illustrates a computer according to one embodiment of thepresent invention, which includes a main body 9201, a housing 9202, adisplay portion 9203, a keyboard 9204, an external connection port 9205,a pointing device 9206, and the like. In the display portion 9203 ofthis computer, light-emitting elements similar to those described in anyof Embodiments 3 to 5 are arranged in matrix. The luminous efficiency ofthe light-emitting elements is high. The light-emitting elements arecapable of emitting light of favorable colors. Therefore, this computerhaving the display portion 9203 which is formed using the light-emittingelements consumes less power. In addition, the computer can haveexcellent color reproducibility and high display quality.

FIG. 5C illustrates a cellular phone according to one embodiment of thepresent invention, which includes a main body 9401, a housing 9402, adisplay portion 9403, an audio input portion 9404, an audio outputportion 9405, operation keys 9406, an external connecting port 9407, anantenna 9408, and the like. In the display portion 9403 of this cellularphone, light-emitting elements similar to those described in any ofEmbodiments 3 to 5 are arranged in matrix. The luminous efficiency ofthe light-emitting elements is high. The light-emitting elements arecapable of emitting light of favorable colors. Therefore, this cellularphone having the display portion 9403 which is formed using thelight-emitting elements consumes less power. In addition, the cellularphone can have excellent color reproducibility and high display quality.

FIG. 5D illustrates a camera according to one embodiment of the presentinvention, which includes a main body 9501, a display portion 9502, ahousing 9503, an external connecting port 9504, a remote controllerreceiving portion 9505, an image receiving portion 9506, a battery 9507,an audio input portion 9508, operation keys 9509, an eye piece portion9510, and the like. In the display portion 9502 of this camera,light-emitting elements similar to those described in any of Embodiments3 to 5 are arranged in matrix. The luminous efficiency of thelight-emitting elements is high. The light-emitting elements are capableof emitting light of favorable colors. Therefore, this camera having thedisplay portion 9502 which is formed using the light-emitting elementsconsumes less power. In addition, the camera can have excellent colorreproducibility and high display quality.

As described above, the application range of the light-emitting devicedescribed in Embodiment 7 is so wide that the light-emitting device canbe applied to electronic devices of every field. An electronic devicewhich consumes less power can be obtained by using the triarylaminederivative described in Embodiment 1. In addition, an electronic devicehaving a display portion capable of providing high-quality display withexcellent color reproducibility can be obtained.

The light-emitting device described in Embodiment 7 can also be used asa lighting apparatus. One embodiment in which the light-emitting devicedescribed in Embodiment 7 is used as a lighting apparatus is describedwith reference to FIG. 6.

FIG. 6 illustrates an example of a liquid crystal display device usingthe light-emitting device described in Embodiment 7 as a backlight. Theliquid crystal display device illustrated in FIG. 6 includes a housing901, a liquid crystal layer 902, a backlight unit 903, and a housing904. The liquid crystal layer 902 is connected to a driver IC 905. Thelight-emitting device described in Embodiment 7 is used as the backlightunit 903, to which current is supplied through a terminal 906.

With the use of the light-emitting device described in Embodiment 7 asthe backlight of the liquid crystal display device, the backlightconsumes less power. Further, the light-emitting device described inEmbodiment 7 is a lighting apparatus with plane light emission and canhave a large area. Therefore, the backlight can have a large area, and aliquid crystal display device having a large area can be obtained.Furthermore, since the light-emitting device described in Embodiment 7is thin, it becomes possible to reduce the thickness of a displaydevice.

FIG. 7 illustrates an example in which the light-emitting devicedescribed in Embodiment 7 is used as a table lamp which is a lightingapparatus. The table lamp illustrated in FIG. 7 includes a housing 2001and a light source 2002, and the light-emitting device described inEmbodiment 7 is used as the light source 2002.

FIG. 8 illustrates an example in which the light-emitting devicedescribed in Embodiment 7 is used as an indoor lighting apparatus 3001.Since the light-emitting device described in Embodiment 7 consumes lesspower, a lighting apparatus that consumes less power can be obtained.Further, since the light-emitting device described in Embodiment 7 canhave a large area, the light-emitting device can be used as a large-arealighting apparatus. Further, since the light-emitting device describedin Embodiment 7 is thin, the light-emitting device can be used for alighting apparatus having reduced thickness. In a room where thelight-emitting device described in Embodiment 7 is used as the indoorlighting apparatus 3001 in this manner, a television device 3002according to one embodiment of the present invention, as illustrated inFIG. 5A, is placed so that public broadcasting and movies can also bewatched.

Example 1 Synthetic Example 1

This example is a synthetic example of4-(1-naphthyl)-4′-phenyltriphenylamine (abbreviation: αNBA1BP), which isthe triarylamine derivative described in Embodiment 1 as the structuralformula (3). Hereinafter, the structure of αNBA1BP is shown.

Step 1: Synthesis of 4-phenyltriphenylamine

In a 300-mL three-neck flask, 9.3 g (40 mmol) of 4-bromobiphenyl, 6.8 g(40 mmol) of diphenylamine, 5.0 g (50 mmol) of sodium tert-butoxide, and10 mg of bis(dibenzylideneacetone)palladium(0) were put, and 100 mL ofxylene and 0.6 mL of tri(tert-butyl)phosphine (a 10 wt % hexanesolution) were added to this mixture. This mixture was deaerated whilebeing stirred under low pressure. After the deaeration, the mixture wasstirred under a nitrogen atmosphere at 130° C. for 3.5 hours. After thestirring, 250 mL of toluene was added to this reaction mixture, and thissuspension was filtrated through Celite (produced by Wako Pure ChemicalIndustries Ltd., Catalogue No. 531-16855, the same product was usedhereinafter), alumina, and then Florisil (produced by Wako Pure ChemicalIndustries Ltd., Catalogue No. 540-00135, the same product was usedhereinafter). The obtained filtrate was washed with water, and magnesiumsulfate was added thereto to dry the filtrate. This mixture wasfiltrated through Celite, alumina, and then Florisil to obtain filtrate.The obtained filtrate was concentrated, methanol was added thereto,ultrasonic waves were applied thereto, and then recrystallizationthereof was performed to obtain 11 g of an objective white powder at ayield of 89%. The synthetic scheme of Step 1 is shown in (a-1) givenbelow.

Step 2: Synthesis of 4-bromo-4′-phenyltriphenylamine

In a 500-mL conical flask, 6.4 g (20 mmol) of 4-phenyltriphenylamine,250 mL of ethyl acetate, and 150 mL of toluene were added and themixture was stirred, and then 3.6 g (20 mmol) of N-Bromosuccinimide(abbreviation: NBS) was added to this solution. After that, this mixturewas stirred for 27.5 hours. After the obtained suspension was washedwith water, moisture was removed by magnesium sulfate. This suspensionwas concentrated and dried to obtain 7.7 g of an objective white powderat a yield of 96%. A synthetic scheme of Step 2 is shown in (b-1) givenbelow.

Step 3: Synthesis of 4-(1-naphthyl)-4′-phenyltriphenylamine(abbreviation: αNBA1BP)

In a 100-mL three-neck flask, 8.0 g (20 mmol) of4-bromo-4′-phenyltriphenylamine, 3.4 g (20 mmol) of 1-naphthaleneboronicacid, 44 mg (0.2 mmol) of palladium(I) acetate, and 60 mg (0.4 mmol) oftri(o-tolyl)phosphine were put, and 20 mL of toluene, 10 mL of ethanol,and 15 mL of a potassium carbonate aqueous solution (2 mol/L) were addedto this mixture. This mixture was deaerated while being stirred underlow pressure. After the deaeration, the mixture was stirred under anitrogen atmosphere at 90° C. for 2.5 hours to be reacted. After thereaction, 150 mL of toluene was added to this reaction mixture, and thissuspension was filtrated through Florisil, silica gel, and then Celite.The obtained filtrate was washed with water, and magnesium sulfate wasadded thereto to remove moisture. This suspension was filtrated throughFlorisil, alumina, silica gel, and then Celite to obtain filtrate. Theobtained filtrate was concentrated, methanol was added thereto,ultrasonic waves were applied thereto, and then recrystallizationthereof was performed to obtain 8.6 g of an objective white solid at ayield of 97%. A synthetic scheme of Step 3 is shown in (c-1) givenbelow.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.43 and that of 4-bromo-4′-phenyltriphenylamine was 0.50.

The compound which was obtained through Step 3 described above wasmeasured by a nuclear magnetic resonance method (¹H NMR). Themeasurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.07 (t, J=7.5 Hz, 1H), 7.22-7.61 (m,17H), 7.83 (d, J=7.8 Hz, 1H), 7.88-7.91 (m, 1H), 8.02-8.05 (m, 1H).

A chart of ¹H NMR is shown in FIG. 9A. Further, FIG. 9B is a chartshowing an enlarged portion in the range of 6 ppm to 9 ppm of FIG. 9A.

Subsequently, molecular weight of the above compound was measured by aTime-of-flight mass spectrometry (abbreviation: TOF-MS) detector (WatersMicromass LCT Premier, manufactured by Waters). A mixture solutioncontaining acetonitrile and 0.1% of a formic acid solution (mixture rateof acetonitrile and the formine acid solution, 80/20 vol/vol) was usedas a solvent. Accordingly, a main peak with a molecular weight of 448.21(mode is ES+) was detected.

From the above measurement results, it was understood that αNBA1BP,which is the triarylamine derivative represented by the above structuralformula (3), was obtained by this synthetic example.

Next, FIG. 10 shows an absorption spectrum of the toluene solution ofαNBA1BP and an absorption spectrum of a thin film of αNBA1BP. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for measurement of the absorption spectra. Thespectrum of the toluene solution of αNBA1BP was measured in a quartzcell. The absorption spectrum of the solution which was obtained bysubtracting the quartz cell from the measured absorption spectrum isshown in FIG. 10. In addition, as for the absorption spectrum of thethin film, a sample was manufactured by evaporation of αNBA1BP over aquartz substrate, and the absorption spectrum thereof from which theabsorption spectrum of the quartz substrate is subtracted, is shown inFIG. 10. In FIG. 10, a horizontal axis represents a wavelength (nm), anda longitudinal axis represents an absorption intensity (given unit).From FIG. 10, in the case of the toluene solution of αNBA1BP, anabsorption peak on a long wavelength side was observed at around 332 nm,and in the case of the thin film, an absorption peak on a longwavelength side was observed at around 339 nm.

Emission spectra of the toluene solution of αNBA1BP and the thin film ofαNBA1BP are shown in FIG. 11. The measurement was performed using anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) in a manner similar to that of the absorption spectrameasurement. The emission spectrum of the toluene solution of αNBA1BPwas measured in a quartz cell, and the emission spectrum of the thinfilm of αNBA1BP was measured by manufacturing a sample by evaporation ofαNBA1BP over a quartz substrate. From FIG. 11, in the case of thetoluene solution of αNBA1BP, the maximum emission wavelength wasobserved at around 404 nm (excitation wavelength: 365 nm), and in thecase of the thin film, the maximum emission wavelength was observed ataround 423 nm (excitation wavelength: 340 nm).

The results of measuring the thin film of αNBA1BP by photoelectronspectrometry (AC-2, product of Riken Keiki Co., Ltd.) in the atmosphereindicated that the HOMO level of αNBA1BP was −5.52 eV. The Tauc plot ofthe absorption spectrum of the thin film in FIG. 10 revealed that theabsorption edge was 3.27 eV. Thus, the energy gap in the solid state ofαNBA1BP was estimated to be 3.27 eV, which means that the LUMO level ofαNBA1BP is −2.25 eV. As thus described, it was understood that αNBA1BPhas a large energy gap of 3.27 eV in the solid state.

In addition, oxidation reaction characteristics of αNBA1BP weremeasured. The oxidation reaction characteristics were examined by acyclic voltammetry (CV) measurement. Further, an electrochemicalanalyzer (ALS model 600A or 600C, manufactured by BAS Inc.) was used forthe measurement.

As for a solution used for the CV measurement, dehydratedN,N-dimethylformamide (abbreviation: DMF, product of Sigma-Aldrich Inc.,99.8%, catalog No. 22705-6) was used as a solvent, andtetra-n-butylammonium perchlorate (abbreviation: n-Bu₄NClO₄, product ofTokyo Chemical Industry Co., Ltd., catalog No. T0836), which was asupporting electrolyte, was dissolved in the solvent such that theconcentration of tetra-n-butylammonium perchlorate was 100 mmol/L.Further, the object to be measured was also dissolved in the solventsuch that the concentration thereof was 2 mmol/L. Further, a platinumelectrode (a PTE platinum electrode, manufactured by BAS Inc.) was usedas a working electrode; a platinum electrode (a VC-3 Pt counterelectrode (5 cm), manufactured by BAS Inc.) was used as an auxiliaryelectrode; and an Ag/Ag⁺ electrode (an RE5 non-aqueous solvent referenceelectrode, manufactured by BAS Inc.) was used as a reference electrode.Note that the measurement was performed at room temperatures (20° C. to25° C.). The scan speed at these CV measurements was set at 0.1 V/s.

A scan for changing the potential of the working electrode with respectto the reference electrode from 0.22 V to 0.70 V and then from 0.70 V to0.22 V was set to one cycle, and measurement was performed for 100cycles.

From the measurement results, it was understood that repetition of theoxidation reduction between an oxidation state and a neutral state hadfavorable characteristics in αNBA1BP without large change in oxidationpeak even after 100 cycles of measurements.

Further, the HOMO level of αNBA1BP was also calculated from the CVmeasurement results.

First, a potential energy (eV) of the reference electrode (Ag/Ag⁺electrode), which was used in this example, with respect to the vacuumlevel was calculated. That is, the Fermi level of the Ag/Ag⁺ electrodewas calculated. It is known that the oxidation-reduction potential offerrocene in methanol is +0.610 V [vs. SHE] with respect to a standardhydrogen electrode (Reference: Christian R. Goldsmith et al., J. Am.Chem. Soc., Vol. 124, No. 1, pp. 83-96, 2002). On the other hand, byusing the reference electrode, which was used in this example, theoxidation-reduction potential of ferrocene in methanol was calculated tobe +0.11 V [vs. Ag/Ag⁺]. Therefore, it was understood that the potentialenergy of the reference electrode, which was used in this example, waslower than that of the standard hydrogen electrode by 0.50 [eV].

Here, it is also known that the potential energy of the standardhydrogen electrode with respect to the vacuum level is −4.44 eV(Reference: Toshihiro Ohnishi and Tamami Koyama, Macromolecular ELmaterial, Kyoritsu Shuppan, pp. 64-67). As described above, it waspossible to calculate the potential energy of the reference electrode,which was used in this example, with respect to the vacuum level asfollows: −4.44−0.50=−4.94 [eV].

Subsequently, the calculation of the HOMO level of αNBA1BP by CVmeasurement is described in detail. An oxidization peak potential E_(pa)of αNBA1BP was 0.61 V. In addition, a reduction peak potential E_(pc)thereof was 0.54 V. Therefore, a half-wave potential (an intermediatepotential between E_(pa) and E_(pc)) can be calculated to be 0.57 V.This shows that αNBA1BP was oxidized by electric energy of 0.57 V [vs.Ag/Ag⁺], and this energy corresponds to the HOMO level. Here, asdescribed above, the potential energy of the reference electrode, whichwas used in this example, with respect to the vacuum level is −4.94[eV]; therefore, it was understood that the HOMO level of αNBA1BP wascalculated as follows: −4.94−0.57=−5.51 [eV].

Example 2 Synthetic Example 2

This example is a synthetic example of4,4′-di-(1-naphthyl)-4″-phenyltriphenylamine (abbreviation: αNBB1BP),which is the triarylamine derivative described in Embodiment 1 as thestructural formula (10). Hereinafter, the structure of αNBB1BP is shown.

Step 1: Synthesis of 4-phenyltriphenylamine

In a manner similar to that of Step 1 in Synthetic Example 1, thesynthesis was performed.

Step 2: Synthesis of 4,4′-dibromo-4″-phenyltriphenylamine

In a 300-mL conical flask, 4.8 g (15 mmol) of 4-phenyltriphenylaminewhich was synthesized in Step 1, 150 mL of ethyl acetate, and 100 mL oftoluene were added and the mixture was stirred, and then 5.3 g (30 mmol)of N-Bromosuccinimide (abbreviation: NBS) was added to this solution.After that, this mixture was stirred for 27.5 hours. After the obtainedsuspension was washed with water, moisture was removed by magnesiumsulfate. This suspension was concentrated and dried to obtain 7.1 g ofan objective white powder at a yield of 99%. A synthetic scheme of Step2 is shown in (b-2) given below.

Step 3: Synthesis of 4,4′-di-(1-naphthyl)-4″-phenyltriphenylamine(abbreviation: αNBB1BP)

In a 100-mL three-neck flask, 1.4 g (3.0 mmol) of4,4′-dibromo-4″-phenyltriphenylamine, 1.1 g (6.6 mmol) of1-naphthaleneboronic acid, 33 mg (0.15 mmol) of palladium(II) acetate,and 91 mg (0.3 mmol) of tri(o-tolyl)phosphine were put, and 20 mL oftoluene, 5 mL of ethanol, and 2.5 mL of a potassium carbonate aqueoussolution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,the mixture was stirred under a nitrogen atmosphere at 90° C. for 6hours to be reacted. After the reaction, 150 mL of toluene was added tothis reaction mixture, and this suspension was filtrated throughFlorisil, alumina, and then Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto to dry the filtrate.After the drying, this suspension was filtrated through Florisil,alumina, and then Celite to obtain filtrate. The obtained filtrate wasconcentrated, methanol was added thereto, ultrasonic waves were appliedthereto, and then recrystallization thereof was performed to obtain 1.2g of an objective white solid at a yield of 53%. Synthetic scheme ofStep 3 is shown in (c-2) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.59 and that of 4,4′-dibromo-4″-phenyltriphenylamine was 0.74.

The compound which was obtained through Step 3 described above wasmeasured by a nuclear magnetic resonance method (¹H NMR). Themeasurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.30-7.64 (m, 25H), 7.85 (d, J=7.8 Hz,2H), 7.90-7.93 (m, 2H), 8.04-8.08 (m, 2H).

A chart of ¹H NMR is shown in FIG. 12A. Further, FIG. 12B is a chartshowing an enlarged portion in the range of 6 ppm to 9 ppm of FIG. 12A.

The molecular weight of the above compound was measured by a TOF-MSdetector (Waters Micromass LCT Premier, manufactured by Waters). Amixture solution containing acetonitrile and 0.1% of a formic acidsolution (mixture rate of acetonitrile and the forminc acid solution,80/20 vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 574.25 (mode is ES+) was detected.

From the above measurement results, it was understood that αNBB1BP,which is the triarylamine derivative represented by the above structuralformula (10), was obtained by this synthetic example.

Next, FIG. 13 shows an absorption spectrum of the toluene solution ofαNBB1BP and an absorption spectrum of a thin film of αNBB1BP. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for measurement of the absorption spectra. Thespectrum of the toluene solution of αNBB1BP was measured in a quartzcell. The absorption spectrum of the solution which was obtained bysubtracting the quartz cell from the measured absorption spectrum isshown in FIG. 13. In addition, as for the absorption spectrum of thethin film, a sample was manufactured by evaporation of αNBB1BP over aquartz substrate, and the absorption spectrum thereof, from which theabsorption spectrum of the quartz substrate is subtracted, is shown inFIG. 13. In FIG. 13, a horizontal axis represents a wavelength (nm), anda longitudinal axis represents an absorption intensity (given unit).From FIG. 13, in the case of the toluene solution of αNBB1BP, anabsorption peak on a long wavelength side was observed at around 341 nm,and in the case of the thin film, an absorption peak on a longwavelength side was observed at around 351 nm.

Emission spectra of the toluene solution of αNBB1BP and the thin film ofαNBB1BP are shown in FIG. 14. The measurement was performed using anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) in a manner similar to that of the absorption spectrameasurement. The emission spectrum of the toluene solution of αNBB1BPwas measured in a quartz cell, and the emission spectrum of the thinfilm of αNBB1BP was measured by manufacturing a sample by evaporation ofαNBB1BP over a quartz substrate. From FIG. 14, in the case of thetoluene solution of αNBB1BP, the maximum emission wavelength wasobserved at around 408 nm (excitation wavelength: 340 nm), and in thecase of the thin film, the maximum emission wavelength was observed ataround 426 nm (excitation wavelength: 368 nm).

The results of measuring the thin film of αNBB1BP by photoelectronspectrometry (AC-2, product of Riken Keiki Co., Ltd.) in the atmosphereindicated that the HOMO level of αNBB1BP was −5.58 eV. The Tauc plot ofthe absorption spectrum of the thin film in FIG. 13 revealed that theabsorption edge was 3.21 eV. Thus, the energy gap in the solid state ofαNBB1BP was estimated to be 3.21 eV, which means that the LUMO level ofαNBB1BP is −237 eV. As thus described, it was understood that αNBB1BPhas a large energy gap of 3.21 eV in the solid state.

In addition, oxidation reaction characteristics of αNBB1BP weremeasured. The oxidation reaction characteristics were examined by acyclic voltammetry (CV) measurement in a manner similar to that ofExample 1.

From the measurement results, it was understood that repetition of theoxidation reduction between an oxidation state and a neutral state hadfavorable characteristics in αNBB1BP without large change in oxidationpeak even after 100 cycles of measurements.

According to the calculation similar to that of Example 1, it wasunderstood that the HOMO level of αNBB1BP was −5.50 [eV].

Example 3 Synthetic Example 3

This example is a synthetic example of 4-(1-naphthyl)-triphenylamine(abbreviation: αNBA1P), which is the triarylamine derivative describedin Embodiment 1 as the structural formula (1). Hereinafter, thestructure of αNBA1P is shown.

Step 1: Synthesis of 4-bromotriphenylamine

To 1.5 L of an ethyl acetate solution containing 54.0 g (220 mmol) oftriphenylamine, 35.6 g (200 mmol) of N-Bromosuccinimide (abbreviation:NBS) was added. After that, this mixture was stirred for 24 hours. Afterthe obtained suspension was concentrated to 1 L, the concentratedsuspension was washed with 1 L of an aqueous solution containing 5% ofsodium acetate. After the washing, this solution was furtherconcentrated to about 50 mL. Then, methanol was added to theconcentrated solution and the solution was precipitated. The obtainedprecipitate was filtered and dried to obtain 46.5 g of an objectivewhite powder at a yield of 73%. A synthetic scheme of Step 1 is shown in(b-3) given below.

Step 2: Synthesis of 4-(1-naphthyl)-triphenylamine (abbreviation:αNBA1P)

In a 200 mL three-neck flask, 9.7 g (30 mmol) of 4-bromotriphenylaminewhich was synthesized in Step 1, 5.7 g (33 mmol) of 1-naphthaleneboronicacid, 67 mg (0.3 mmol) of palladium(II) acetate, and 91 mg (0.3 mmol) oftri(o-tolyl)phosphine were put, and 50 mL of toluene, 20 mL of ethanol,and 20 mL of a potassium carbonate aqueous solution (2 mol/L) were addedto this mixture. This mixture was deaerated while being stirred underlow pressure. After the deaeration, the mixture was stirred under anitrogen atmosphere at 90° C. for 2 hours to be reacted. After thereaction, 150 mL of toluene was added to this reaction mixture, and thissuspension was filtrated through Florisil, silica gel, and then Celite.The obtained filtrate was washed with sodium hydrogen carbonate aqueoussolution and water in this order, and magnesium sulfate was addedthereto to dry the filtrate. After the drying, this suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and dried toobtain 11 g of an objective white solid at a yield of 99%. A syntheticscheme of Step 2 is shown in (c-3) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.48 and that of 4-bromotriphenylamine was 0.55.

The molecular weight of the white solid which was obtained in Step 2 wasmeasured by a TOF-MS detector (Waters Micromass LCT Premier,manufactured by Waters). A mixture solution containing acetonitrile and0.1% of a formic acid solution (mixture rate of acetonitrile and theforminc acid solution, 80/20 vol/vol) was used as a solvent.Accordingly, a main peak with a molecular weight of 372.17 (mode is ES+)was detected and it was confirmed that objective αNBA1P was obtained.

Example 4 Synthetic Example 4

This example is a synthetic example of4,4′-di-(1-naphthyl)triphenylamine (abbreviation: αNBB1P), which is thetriarylamine derivative described in Embodiment 1 as the structuralformula (7). Hereinafter, the structure of αNBB1P is shown.

Step 1: Synthesis of 4,4′-dibromotriphenylamine

After 12 g (50 mmol) of triphenylamine was dissolved in 250 mL of ethylacetate in a 500-mL conical flask, 18 g (100 mmol) of N-Bromosuccinimide(abbreviation: NBS) was added to this solution. After that, this mixturewas stirred at room temperature for 24 hours to be reacted. Aftercompletion of the reaction, this mixture solution was washed with water,and magnesium sulfate was added thereto to remove moisture. Thismixture: solution was filtrated, and the obtained filtrate wasconcentrated and dried to obtain 20 g of an objective white solid at ayield of 99%. A synthesis scheme of Step 1 is shown in (b-4) givenbelow.

Step 2: Synthesis of 4,4′-di-(1-naphthyl)triphenylamine (abbreviation:αNBB1P)

In a 100-mL three-neck flask, 6.0 g (15 mmol) of4,4′-dibromotriphenylamine which was synthesized in Step 1, 52 g (30mmol) of 1-naphthaleneboronic acid, 2.0 mg (0.01 mmol) of palladium(II)acetate, and 6.0 mg (0.02 mmol) of tri(o-tolyl)phosphine were put, and20 mL of toluene, 5 mL of ethanol, and 20 mL of a potassium carbonateaqueous solution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,the mixture was stirred under a nitrogen atmosphere at 90° C. for 4.5hours to be reacted. After the reaction, 150 mL of toluene was added tothis reaction mixture, and this suspension was filtrated throughFlorisil and then Celite. The obtained filtrate was washed with water,and magnesium sulfate was added thereto to remove moisture. Thissuspension was filtrated through Florisil, alumina, silica gel, and thenCelite to obtain filtrate. The obtained filtrate was concentrated,methanol was added thereto, ultrasonic waves were applied thereto, andthen recrystallization thereof was performed to obtain 6.4 g of anobjective white solid at a yield of 86%. A synthetic scheme of Step 2 isshown in (c-4) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.53 and that of 4,4′-dibromotriphenylamine was 0.69.

The molecular weight of the white solid which was obtained in Step 2 wasmeasured by a TOF-MS detector (Waters Micromass LCT Premier,manufactured by Waters). A mixture solution containing acetonitrile and0.1% of a formic acid solution (mixture rate of acetonitrile and theforminc acid solution, 80/20 vol/vol) was used as a solvent.Accordingly, a main peak with a molecular weight of 498.22 (mode is ES+)was detected and it was confirmed that objective αNBB1P was obtained.

Example 5 Synthetic Example 5

This example is a synthetic example of[4′-(1-naphthyl)biphenyl-4-yl]diphenylamine (abbreviation: αNTA1P),which is the triarylamine derivative described in Embodiment 1 as thestructural formula (2). Hereinafter, the structure of αNTA1P is shown.

Step 1: Synthesis of 4-(4-bromophenyl)-triphenylamine

In a 500-mL three-neck flask, 22 g (70 mmol) of 4,4′-dibromobiphenyl,8.5 g (50 mmol) of diphenylamine, 1.9 g (10 mmol) of copper(I) iodide,2.6 g (10 mmol) of 18-crown-6-ether, 6.9 g (50 mmol) of potassiumcarbonate, and 50 mL of1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (abbreviation: DMPU)were put, and the mixture was stirred under a nitrogen atmosphere at180° C. for 37 hours to be reacted. After the reaction, 500 mL oftoluene was added to this reaction mixture, and this suspension wasfiltrated through Florisil, silica gel, and then Celite. The obtainedfiltrate was washed with water, and magnesium sulfate was added theretoto remove moisture. This suspension was filtrated through Florisil,alumina, silica gel, and then Celite to obtain filtrate. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography (developing solvent, toluene: hexane=1:4). The obtainedfraction was concentrated, hexane and methanol were added thereto,ultrasonic waves were applied thereto, and then recrystallizationthereof was performed to obtain 5.3 g of an objective white powder at ayield of 27%. A synthetic scheme of Step 1 is shown in (b′-5) givenbelow.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.5 and that of 4,4′-dibromobiphenyl was 0.59.

Step 2: Synthesis of [4′-(1-naphthyl)biphenyl-4-yl]diphenylamine(abbreviation: αNTA1P)

In a 100-mL three-neck flask, 4.0 g (10 mmol) of4-(4-bromophenyl)-triphenylamine which was synthesized in Step 1, 1.7 g(10 mmol) of 1-naphthaleneboronic acid, 11 mg (0.05 mmol) ofpalladium(II) acetate, and 15 mg (0.05 mmol) of tri(o-tolyl)phosphinewere put, and 20 mL of toluene, 5 mL of ethanol, and 10 mL of apotassium carbonate aqueous solution (2 mol/L) were added to thismixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, the mixture was stirred under a nitrogenatmosphere at 90° C. for 7 hours to be reacted. After the reaction, 150mL of toluene was added to this reaction mixture, and this suspensionwas filtrated through silica gel, alumina, and then Celite. The obtainedfiltrate was washed with water, and magnesium sulfate was added theretoto remove moisture. This suspension was filtrated through silica gel,alumina, and then Celite to obtain filtrate. The obtained filtrate wasconcentrated, methanol was added thereto, ultrasonic waves were appliedthereto, and then recrystallization thereof was performed to obtain 3.6g of an objective white powder at a yield of 80%. A synthetic scheme ofStep 2 is shown in (c-5) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.58 and that of 1-(4′-bromobiphenyl-4-yl)naphthalene was 0.65.

The white solid which was obtained through Step 2 described above wasmeasured by a nuclear magnetic resonance method (¹H NMR). Themeasurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.05 (t, J=7.8 Hz, 2H), 7.12-7.58 (m,18H), 7.70 (d, J=7.8 Hz, 2H), 7.87 (d, J=8.1 Hz, 1H), 7.92 (d, J=7.8 Hz,1H), 7.99 (d, J=8.7 Hz, 1H)

The molecular weight of the above white solid was measured by a TOF-MSdetector (Waters Micromass LCT Premier, manufactured by Waters). Amixture solution containing acetonitrile and 0.1% of a formic acidsolution (mixture rate of acetonitrile and the forminc acid solution,80/20 vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 448.20 (mode is ES+) was detected.

From the above measurement results, it was understood that αNTA1P, whichis the triarylamine derivative according to one embodiment of thepresent invention represented by the above structural formula (2), wasobtained by this synthetic example.

Example 6 Synthetic Example 6

This example is a synthetic example of4,4′-di-(2-naphthyl)triphenylamine (abbreviation: βNBB1P), which is thetriarylamine derivative described in Embodiment 1 as the structuralformula (19). Hereinafter, the structure of 3NBB1P is shown.

Step 1: Synthesis of 4,4′-dibromotriphenylamine

In a manner similar to that of Step 1 in Synthesis Example 4, thesynthesis was performed.

Step 2: Synthesis of 4,4′-di-(2-naphthyl)triphenylamine (abbreviation:βNBB1P)

In a 300-mL three-neck flask, 6.0 g (15 mmol) of4,4′-dibromotriphenylamine which was synthesized in Step 1, 6.2 g (36mmol) of 2-naphthaleneboronic acid, 16 mg (0.1 mmol) of palladium(II)acetate, and 21 mg (0.1 mmol) of tri(o-tolyl)phosphine were put, and 50mL of toluene, 20 mL of ethanol, and 20 mL of a potassium carbonateaqueous solution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,the mixture was stirred under a nitrogen atmosphere at 90° C. for 4.5hours to be reacted. After the reaction, 150 mL of toluene was added tothis reaction mixture, and this suspension was filtrated throughFlorisil, silica gel, and then Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto to remove moisture.This suspension was filtrated through Florisil, alumina, silica gel, andthen Celite to obtain filtrate. The obtained filtrate was concentrated,hexane was added thereto, ultrasonic waves were applied thereto, andthen recrystallization thereof was performed to obtain 5.6 g of anobjective white powder at a yield of 75%. A synthetic scheme of Step 2is shown in (c-6) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.53 and that of 4,4′-dibromotriphenylamine was 0.78.

The molecular weight of the white powder which was obtained in Step 2was measured by a TOF-MS detector (Waters Micromass LCT Premier,manufactured by Waters). A mixture solution containing acetonitrile and0.1% of a formic acid solution (mixture rate of acetonitrile and theformine acid solution, 80/20 vol/vol) was used as a solvent.Accordingly, a main peak with a molecular weight of 498.22 (mode is ES+)was detected and it was confirmed that objective βNBB1P was obtained.

Example 7 Synthetic Example 7

This example is a synthetic example of4-(1-naphthyl)-4′-phenyltriphenylamine (abbreviation: αNBA1BP), which isthe triarylamine derivative described in Embodiment 1 as the structuralformula (3), in which a method different from that of Synthetic Example1 is used. Hereinafter, the structure of αNBA1BP is shown.

Step 1: Synthesis of 4-phenyl-diphenylamine

In a 1000-mL three-neck flask, 51 g (220 mmol) of 4-bromobiphenyl, 23 g(250 mmol) of aniline, 50 g (500 mmol) of sodium tert-butoxide, and 250mg (0.4 mmol) of bis(dibenzylideneacetone)palladium(0) were put, and theatmosphere in the flask was substituted by nitrogen. To this mixture,500 mL of dehydrated toluene was added. This mixture was deaerated whilebeing stirred under low pressure. After the deaeration, 3.0 mL (1.5mmol) of tri(tert-butyl)phosphine (a 10 wt % hexane solution) was addedthereto. Next, this mixture was stirred under a nitrogen atmosphere at90° C. for 4.5 hours to be reacted. After the reaction, 600 mL oftoluene was added to this reaction mixture, and this suspension wasfiltrated through Florisil and then Celite. The obtained filtrate waswashed with water, and magnesium sulfate was added thereto to removemoisture. This suspension was filtrated through Florisil and then Celiteto obtain filtrate. The obtained filtrate was concentrated, hexane wasadded thereto, ultrasonic waves were applied thereto, and thenrecrystallization thereof was performed to obtain 40 g of an objectivewhite powder of 4-phenyl-diphenylamine at a yield of 73%. A syntheticscheme of Step 1 is shown in (a-7) given below.

Step 2: Synthesis of 1-(4-bromophenyl)-naphthalene

In a 500-mL three-neck flask, 46 g (160 mmol) of 4-bromoiodobenzene, 24g (140 mmol) of 1-naphthaleneboronic acid, 45 mg (0.2 mmol) ofpalladium(II) acetate, and 60 mg (0.2 mmol) of tri(o-tolyl)phosphinewere put, and 100 mL of toluene, 20 mL of ethanol, and 11 mL of apotassium carbonate aqueous solution (2 mol/L) were added to thismixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, the mixture was stirred under a nitrogenatmosphere at 90° C. for 4 hours to be reacted. After the reaction, 500mL of toluene was added to this reaction mixture, and this suspensionwas filtrated through Florisil and then Celite. The obtained filtratewas washed with water, and magnesium sulfate was added thereto to removemoisture. This suspension was filtrated through Florisil and then Celiteto obtain filtrate. The obtained filtrate was concentrated and purifiedby silica gel column chromatography (developing solvent, hexane). Theobtained fraction was concentrated to obtain 25 g of an objectivecolorless transparent liquid at a yield of 62%. A synthetic scheme ofStep 2 is shown in (b-7) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, hexane) was 0.38 and that of4-bromoiodobenzene was 0.57.

Step 3: Synthesis of 4-(1-naphthyl)-4′-phenyltriphenylamine

In a 300-mL three-neck flask, 5.7 g (20 mmol) of1-(4-bromophenyl)-naphthalene which was synthesized in Step 2, 4.9 g (20mmol) of 4-phenyl-diphenylamine which was synthesized in Step 1, 2.5 g(25 mmol) of sodium tert-butoxide, and 11 mg (0.02 mmol) ofbis(dibenzylideneacetone)palladium(0) were put, and the atmosphere ofthe flask was substituted by nitrogen. To this mixture, 50 mL ofdehydrated xylene was added. This mixture was deaerated while beingstirred under low pressure. After the deaeration, 0.1 mL (0.06 mmol) oftri(tert-butyl)phosphine (a 10 wt % hexane solution) was added thereto.This mixture was stirred under a nitrogen atmosphere at 110° C. for 6.5hours to be reacted. After the reaction, 150 mL of toluene was added tothis reaction mixture, and this suspension was filtrated throughFlorisil, silica gel, and then Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto to remove moisture.This suspension was filtrated through Florisil, silica gel, and thenCelite to obtain filtrate. The obtained filtrate was concentrated andpurified by silica gel column chromatography (developing solvent,toluene: hexane=1:9). The obtained fraction was concentrated, acetoneand hexane were added thereto, ultrasonic waves were applied thereto,and then recrystallization thereof was performed to obtain 7.3 g of anobjective white powder at a yield of 98%. A synthetic scheme of Step 3is shown in (c-7) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.31, that of 1-(4-bromophenyl)-naphthalene was 0.60, and that of4-phenyl-diphenylamine was 0.16.

The molecular weight of the white powder obtained in Step 3 was measuredby a TOF-MS detector (Waters Micromass LCT Premier, manufactured byWaters). A mixture solution containing acetonitrile and 0.1% of a formicacid solution (mixture rate of acetonitrile and the forminc acidsolution, 80/20 vol/vol) was used as a solvent. Accordingly, a main peakwith a molecular weight of 448.21 (mode is ES+) was detected. From theabove measurement results, it was understood that αNBA1BP, which is thetriarylamine derivative represented by the above structural formula (3),was obtained by this synthetic example.

Example 8 Synthetic Example 8

This example is a synthetic example of4,4′-di-(1-naphthyl)triphenylamine (abbreviation: αNBB1P), which is thetriarylamine derivative described in Embodiment 1 as the structuralformula (7), in which a method different from that of Synthetic Example4 is used. Hereinafter, the structure of αNBB1P is shown.

Step 1: Synthesis of 1-(4-bromophenyl)-naphthalene

In a manner similar to that of Step 2 in Synthetic Example 7, thesynthesis was performed.

Step 2: Synthesis of 4,4′-di-(1-naphthyl)triphenylamine (abbreviation:αNBB1P)

In a 100-mL three-neck flask, 3.4 g (12 mmol) of1-(4-bromophenyl)-naphthalene which was synthesized in Step 1, 0.5 g (5mmol) of aniline, 1.5 g (15 mmol) of sodium tert-butoxide, 10 mg (0.05mmol) of palladium(II) acetate, 10 mg (0.05 mmol) of1,1-bis(diphenylphosphino)ferrocene (abbreviation: DPPF), and 15 mL oftoluene were put. This mixture was deaerated while being stirred underlow pressure. After the deaeration, the mixture was stirred under anitrogen atmosphere at 80° C. for 5 hours to be reacted. After thereaction, 150 mL of toluene was added to this reaction mixture, and thissuspension was filtrated through Florisil and then Celite. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography (developing solvent, toluene: hexane=1:4). The obtainedfraction was concentrated, methanol was added thereto, ultrasonic waveswere applied thereto, and then recrystallization thereof was performedto obtain 1.9 g of an objective white powder at a yield of 77%. Asynthetic scheme of Step 2 is shown in (c-8) given below.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.22 and that of 1-bromo-4-(1-naphthyl)benzene was 0.53.

Example 9

In this example, two light-emitting elements (a light-emitting element 2and a light-emitting element 3) using the triarylamine derivativedescribed in Embodiment 1 as a material that forms a hole transportinglayer adjacent to a light-emitting layer emitting blue fluorescence weremanufactured, and a performance test for the light-emitting elements wasalso carried out. Note that in this example, light-emitting elements (alight-emitting element 1 and a light-emitting element 4) without usingthe above triarylamine derivative were also manufactured for comparison,and a performance test for the light-emitting elements was also carriedout.

In addition, a molecular structure of an organic compound (αNBA1BP,description of which is omitted because the structure thereof is shownin Example 1 and Example 2) which is used in this example is shown instructural formulae (i) to (vi) given below. In FIG. 1A, the elementstructure in which an electron injecting layer is provided between theelectron transporting layer 114 and the second electrode 104 wasemployed.

<<Manufacture of Light-Emitting Elements 1 to 4>>

First, a glass substrate 101 over which indium tin oxide containingsilicon (ITSO) with a thickness of 110 nm had been formed as a firstelectrode 102 was prepared. The periphery of surface of the ITSO wascovered with a polyimide film so that an area of 2 mm×2 mm of thesurface was exposed. The electrode area was 2 mm×2 mm. As a pretreatmentfor forming the light-emitting element over the substrate, the surfaceof the substrate was washed with water and baked at 200° C. for onehour, and then a UV ozone treatment was performed for 370 seconds. Then,the substrate was transferred into a vacuum evaporation apparatus whosepressure was reduced to about 10⁻⁴ Pa, vacuum baking at 170° C. for 30minutes was performed in a heating chamber of the vacuum evaporationapparatus, and then the substrate was cooled down for about 30 minutes.

Next, the substrate 101 was fixed to a holder provided in the vacuumevaporation apparatus such that the surface of the substrate 101provided with ITSO is faced downward.

After the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation:NPB) represented by the above structure formula (i) and molybdenum(VI)oxide were co-evaporated to have a mass ratio of NPB:molybdenum(VI)oxide=4:1, whereby a hole injecting layer 111 was formed. The thicknessof the hole injecting layer 111 was 50 nm. Note that the co-evaporationis an evaporation method in which some different substances areevaporated from some different evaporation sources at the same time.

Subsequently, a hole transporting layer 112 was formed in such a mannerthat the light-emitting elements 1 to 4 were each evaporated to have athickness of 10 nm using, for the light-emitting element 1, NPB which iswidely used as a material for a hole transporting layer, for thelight-emitting element 2, αNBA1BP which is the triarylamine derivativedescribed in Embodiment 1; for the light-emitting element 3, αNBB1BPwhich is the triarylamine derivative described in Embodiment 1; and forthe light-emitting element 4,4-(1-naphthyl)-4′-phenyltriphenylamine(abbreviation: αNBABP) which is the known substance represented by theabove structural formula (ii).

Further, a light-emitting layer 113 was formed over thehole-transporting layer 112 in such a manner that9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA)represented by the above structure formula (iii) and4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA) represented by the above structure formula (iv)were co-evaporated to have a mass ratio of CzPA: PCBAPA=1:0.1. Thethickness of the light-emitting layer 113 was 30 nm.

Then, an electron transporting layer 114 was formed by evaporatingtris(8-quinolinolato)aluminum(III) (abbreviation: Alq) represented bythe above structural formula (v) with a thickness of 10 nm and, overAlq, bathophenanthroline (abbreviation: BPhen) represented by the abovestructural formula (vi) with a thickness of 20 nm. Further, lithiumfluoride was evaporated to a thickness of 1 nm over the electrontransporting layer 114, whereby an electron injecting layer was formed.Lastly, aluminum was formed with a thickness of 200 nm as a secondelectrode 104 which serves as a cathode, whereby the light-emittingelements 1 to 4 were completed. Note that in the above evaporationprocess, evaporation was all performed by a resistance heating method.

<<Operating Characteristics of Light-Emitting Elements 1 to 4>>

The light-emitting elements 1 to 4 thus obtained were sealed in a glovebox under a nitrogen atmosphere without being exposed to atmosphericair. Then, the operating characteristics of the light-emitting elementswere measured. Note that the measurement was carried out at a roomtemperature (in the atmosphere kept at 25° C.).

Voltage vs. luminance characteristics of each light-emitting element areshown in FIG. 15, luminance vs. current efficiency characteristics ofeach light-emitting element are shown in FIG. 16, and luminance vs.power efficiency characteristics of each light-emitting element areshown in FIG. 17. In FIG. 15, a longitudinal axis represents a luminance(cd/m²), and a horizontal axis represents a voltage (V). In FIG. 16, alongitudinal axis represents a current efficiency (cd/A), and ahorizontal axis represents a luminance (cd/m²). In FIG. 17, alongitudinal axis represents a power efficiency (lm/W), and a horizontalaxis represents a luminance (cd/m²).

It is understood from the graphs that the light-emitting element 2 andthe light-emitting element 3 using the triarylamine derivative describedin Embodiment 1 as a hole transporting layer show luminance vs. currentefficiency characteristics which are preferable to those of thelight-emitting element 1 and the light-emitting element 4, and havepreferable luminous efficiency. In addition, as for the power efficiency(lm/W) of each light-emitting element at a luminance of 1000 cd/m², thelight-emitting element 1 was 4.1, the light-emitting element 2 was 6.3,the light-emitting element 3 was 6.2, and the light-emitting element 4was 53. Accordingly, it was understood that, as compared to thelight-emitting element 1 and the light-emitting element 4, thelight-emitting element 2 and the light-emitting element 3 can performdriving with low power consumption, which is preferable.

FIG. 18 shows emission spectra when a current of 1 mA was made to flowin the manufactured light-emitting elements 1 to 4. In FIG. 18, ahorizontal axis represents an emission wavelength (nm), and alongitudinal axis represents an emission intensity. FIG. 18 shows acomparative value of each light-emitting element with the same maximumemission intensity. It is understood from FIG. 18 that each of thelight-emitting elements 1 to 4 emits preferable blue light which isresulted from PCBAPA which is a light-emitting substance.

Next, when these elements were driven under the condition of fixedcurrent density with an initial luminance set at 1000 cd/m², each of thelight-emitting elements similarly showed preferable characteristics inthe luminance half-decay period.

Example 10

In this example, a light-emitting element (a light-emitting element 7)using the triarylamine derivative described in Embodiment 1 as amaterial that forms a hole transporting layer adjacent to alight-emitting layer emitting green phosphorescence was manufactured,and a performance test for the light-emitting element was also carriedout. Note that in this example, light-emitting elements (alight-emitting element 5 and a light-emitting element 6) without usingthe above triarylamine derivative were also manufactured for comparison,and a performance test for the light-emitting elements was also carriedout.

A molecular structure of an organic compound (description is omitted forthose already have shown) which is used in this example is shown instructural formulae (vii) and (viii) given below. In FIG. 1A, theelement structure in which an electron injecting layer is providedbetween the electron transporting layer 114 and the second electrode 104was employed.

<<Manufacture of Light-Emitting Elements 5 to 7>>

First, a glass substrate 101 over which indium tin oxide containingsilicon (ITSO) with a thickness of 110 nm had been formed as a firstelectrode 102 was prepared. The periphery of surface of the ITSO wascovered with a polyimide film so that an area of 2 mm×2 mm of thesurface was exposed. The electrode area was 2 mm×2 mm. As a pretreatmentfor forming the light-emitting element over the substrate, the surfaceof the substrate was washed with water and baked at 200° C. for onehour, and then a UV ozone treatment was performed for 370 seconds. Then,the substrate was transferred into a vacuum evaporation apparatus whosepressure was reduced to about 10⁻⁴ Pa, vacuum baking at 170° C. for 30minutes was performed in a heating chamber of the vacuum evaporationapparatus, and then the substrate was cooled down for about 30 minutes.

Next, the substrate 101 was fixed to a holder provided in the vacuumevaporation apparatus such that the surface of the substrate 101provided with ITSO is faced downward.

After the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation:NPB) represented by the above structure formula (i) and molybdenum(VI)oxide were co-evaporated to have a mass ratio of NPB:molybdenum(VI)oxide=4:1, whereby a hole injecting layer 111 was formed. The thicknessof the hole injecting layer 111 was 40 nm. Note that the co-evaporationis an evaporation method in which some different substances areevaporated from some different evaporation sources at the same time.

Subsequently, a hole transporting layer 112 was formed in such a mannerthat the light-emitting elements 5 to 7 were each evaporated to have athickness of 20 nm using, for the light-emitting element 5, NPB which iswidely used as a material for a hole transporting layer, for thelight-emitting element 6, αNBABP the structure of which is shown inExample 6 as the structural formula (ii); and for the light-emittingelement 7, αNBA1BP which is the triarylamine derivative according to oneembodiment of the present invention described in Embodiment 1.

Further, a light-emitting layer 113 was formed over thehole-transporting layer 112 in such a manner that4-(9H-carbazol-9-yl)-4′-(5-phenyl-1,3,4-oxadiazol-2-yl)triphenylamine(abbreviation: YGAO11) represented by the above structure formula (vii)and bis[2-phenylpyridinato-N,C^(2′)]iridium(II) acetylacetonate(abbreviation: Ir(ppy)₂acac) represented by the above structure formula(viii) were co-evaporated to have a mass ratio ofYGAO11:Ir(ppy)₂acac=1:0.05. The thickness of the light-emitting layer113 was 40 nm.

Then, an electron transporting layer 114 was formed by evaporatingbathophenanthroline (abbreviation: BPhen) represented by the abovestructural formula (vi) with a thickness of 30 nm. Further, lithiumfluoride was evaporated to a thickness of 1 nm over the electrontransporting layer 114, whereby an electron injecting layer was formed.Lastly, aluminum was formed with a thickness of 200 nm as the secondelectrode 104 which serves as a cathode, whereby the light-emittingelements 5 to 7 were completed. Note that in the above evaporationprocess, evaporation was all performed by a resistance heating method.

<<Operating Characteristics of Light-Emitting Elements 5 to 7>>

The light-emitting elements 5 to 7 thus obtained were sealed in a glovebox under a nitrogen atmosphere without being exposed to atmosphericair. Then, the operating characteristics of the light-emitting elementswere measured. Note that the measurement was carried out at a roomtemperature (in the atmosphere kept at 25° C.).

Current density vs. luminance characteristics of each light-emittingelement are shown in FIG. 19, luminance vs. current efficiencycharacteristics of each light-emitting element are shown in FIG. 20,luminance vs. power efficiency characteristics of each light-emittingelement are shown in FIG. 21, and voltage vs. luminance characteristicsof each light-emitting element are shown in FIG. 22. In FIG. 19, alongitudinal axis represents a luminance (cd/m²), and a horizontal axisrepresents a current density (mA/cm²). In FIG. 20, a longitudinal axisrepresents a current efficiency (cd/A), and a horizontal axis representsa luminance (cd/m²). In FIG. 21, a longitudinal axis represents a powerefficiency (lm/W), and a horizontal axis represents a luminance (cd/m²).In FIG. 22, a longitudinal axis represents a luminance (cd/m²), and ahorizontal axis represents a voltage (V).

It is understood from the graphs that the light-emitting element 7 usingthe triarylamine derivative described in Embodiment 1 as a holetransporting layer show luminance vs. current efficiency characteristicswhich are preferable to those of the light-emitting element 5 and thelight-emitting element 6, and have preferable luminous efficiency. Inaddition, as for the power efficiency (lm/W) of each light-emittingelement at a luminance of 1000 cd/m², the light-emitting element 5 was33, the light-emitting element 6 was 40, and the light-emitting element7 was 50. Accordingly, it was understood that, as compared to thelight-emitting element 5 and the light-emitting element 6, thelight-emitting element 7 can perform driving with low power consumption,which is preferable.

In addition, a CIE chromaticity coordinate of each of the light-emittingelements 5 to 7 at a luminance of 1000 cd/m² was (x=0.35, y=0.62), andgreen light emission which is derived from Ir(ppy)₂acac was exhibited.

From the above results, since the triarylamine derivative described inEmbodiment 1 shows high luminous efficiency even when it is used for ahole transporting layer adjacent to a light-emitting layer emittinggreen phosphoresce, it is understood that the above triarylaminederivative is a substance having high triplet energy.

Example 11

In this example, four light-emitting elements (a light-emitting element9, a light-emitting element 10, a light-emitting element 11, and alight-emitting element 12) using a composite material in which anacceptor substance is contained in the triarylamine derivative describedin Embodiment 1 as a material that forms a hole injecting layer weremanufactured, and a performance test for the light-emitting elementswere also carried out. Note that in this example, a light-emittingelement (a light-emitting element 8) without using the abovetriarylamine derivative was also manufactured for comparison, and aperformance test for the light-emitting element was also carried out.

Note that since the organic compounds used in this example are alreadyall described in this specification, description of a molecularstructure thereof is omitted. In FIG. 1A, the element structure in whichan electron injecting-layer is provided between the electrontransporting layer 114 and the second electrode 104 with thelight-emitting layer 113 having a two-layer structure was employed.

<<Manufacture of Light-Emitting Elements 8 to 12>>

First, a glass substrate 101 over which indium tin oxide containingsilicon (ITSO) with a thickness of 110 nm had been formed as a firstelectrode 102 was prepared. The periphery of surface of the ITSO wascovered with a polyimide film so that an area of 2 mm×2 mm of thesurface was exposed. The electrode area was 2 mm×2 mm. As a pretreatmentfor forming the light-emitting element over the substrate, the surfaceof the substrate was washed with water and baked at 200° C. for onehour, and then a UV ozone treatment was performed for 370 seconds. Then,the substrate was transferred into a vacuum evaporation apparatus whosepressure was reduced to about 10⁻⁴ Pa, vacuum baking at 170° C. for 30minutes was performed in a heating chamber of the vacuum evaporationapparatus, and then the substrate was cooled down for about 30 minutes.

Next, the substrate 101 was fixed to a holder provided in the vacuumevaporation apparatus such that the surface of the substrate 101provided with ITSO is faced downward.

After the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa, in the light-emitting element 8 which is the comparativeelement, NPB and molybdenum(VI) oxide were co-evaporated to have a massratio of NPB:molybdenum(VI) oxide=4:1, whereby a hole injecting layer111 was formed. In addition, in the light-emitting elements 9 to 12which are each an example of a light-emitting element according to oneembodiment of the present invention, αNBA1BP, which is the triarylaminederivative described in Embodiment 1, is used instead of NPB to beco-evaporated with molybdenum(VI) oxide, whereby the hole injectinglayer 111 was formed. Note that the evaporation was performed so thatthe mass ratio of αNBA1BP and molybdenum(VI) oxide in the light-emittingelement 9 was 8:1; the mass ratio in the light-emitting element 10 was4:1; and the mass ratio in the light-emitting elements 11 and 12 was2:1. Each of the hole injecting layers had a thickness of 50 nm. Notethat the co-evaporation is an evaporation method in which some differentsubstances are evaporated from some different evaporation sources at thesame time.

Subsequently, a hole transporting layer 112 was formed in such a mannerthat the light-emitting elements 8 to 12 are each evaporated to have athickness of 10 nm using, for the light-emitting elements 8 to 11, NPBwhich is widely used as a material for a hole transporting layer, andfor the light-emitting element 12, αNBA1BP which is the triarylaminederivative described in Embodiment 1.

Further, a light-emitting layer 113 was formed over thehole-transporting layer 112 in such a manner that PCBAPA was evaporatedwith a thickness of 25 nm and then CzPA and PCBAPA were co-evaporatedwith a thickness of 30 nm to have a mass ratio of CzPA:PCBAPA=10:1.

Then, an electron transporting layer 114 was formed by evaporating Alqwith a thickness of 10 nm and BPhen over the film of Alq with athickness of 20 nm. Further, lithium fluoride was evaporated to athickness of 1 nm over the electron transporting layer 114, whereby anelectron injecting layer was formed. Lastly, aluminum was formed with athickness of 200 nm as the second electrode 104 which serves as acathode, whereby the light-emitting elements 8 to 12 were completed.Note that in the above evaporation process, evaporation was allperformed by a resistance heating method.

<<Operating Characteristics of Light-Emitting Elements 8 to 12>>

The light-emitting elements 8 to 12 thus obtained were sealed in a glovebox under a nitrogen atmosphere without being exposed to atmosphericair. Then, the operating characteristics of the light-emitting elementswere measured. Note that the measurement was carried out at a roomtemperature (in the atmosphere kept at 25° C.).

Voltage vs. luminance characteristics of each light-emitting element areshown in FIG. 23, luminance vs. current efficiency characteristics ofeach light-emitting element are shown in FIG. 24, and luminance vs.power efficiency characteristics of each light-emitting element areshown in FIG. 25. In FIG. 23, a longitudinal axis represents a luminance(cd/m²), and a horizontal axis represents a voltage (V). In FIG. 24, alongitudinal axis represents a current efficiency (cd/A), and ahorizontal axis represents a luminance (cd/m²). In FIG. 25, alongitudinal axis represents a power efficiency (lm/W), and a horizontalaxis represents a luminance (cd/m²).

It was understood from FIG. 24 that the light-emitting elements 9 to 12using the triarylamine derivative, which is described in Embodiment 1,together with the acceptor substance as a composite material for a holeinjecting layer show luminance vs. current efficiency characteristicswhich are preferable to those of the light-emitting element 8 using NPBinstead of the triarylamine derivative, which is described in Embodiment1, and have preferable luminous efficiency. In addition, it isunderstood from FIG. 25 that, as for the power efficiency (lm/W) of eachlight-emitting element at a luminance of 1000 cd/m², the light-emittingelement 8 was 4.7, the light-emitting element 9 was 4.9, thelight-emitting element 10 was 4.9, the light-emitting element 11 was4.8, and the light-emitting element 12 was 5.0. Accordingly, it wasunderstood that, as compared to the light-emitting element 8, thelight-emitting elements 9 to 12 can perform driving with low powerconsumption, which is preferable.

FIG. 26 shows emission spectra when a current of 1 mA was made to flowin the manufactured light-emitting elements 8 to 12. In FIG. 26, ahorizontal axis represents an emission wavelength (nm), and alongitudinal axis represents an emission intensity. FIG. 26 shows acomparative value of each light-emitting element with the same maximumemission intensity. It is understood from FIG. 26 that each of thelight-emitting elements 8 to 12 emits preferable blue light which isresulted from PCBAPA which is a light-emitting substance.

Next, time vs. normalized luminance characteristics of each element areshown in FIG. 27. A horizontal axis represents a time (h), and alongitudinal axis represents a normalized luminance (%). When theseelements were driven under the condition of fixed current density withan initial luminance set at 1000 cd/m², each of the light-emittingelements similarly showed preferable characteristics in reliability.Note that in FIG. 27, the trajectories of the graph seem one becausealmost the same trajectories are drawn in each of the light-emittingelements (the light-emitting elements 8 to 12).

It was understood from the light-emitting elements 8 to 12 that thetriarylamine derivative, which is described in Embodiment 1, togetherwith an acceptor substance can be preferably used for the hole injectinglayer 111. In addition, it was understood from the light-emittingelement 12 that the triarylamine derivative described in Embodiment 1 isa preferable material that can be used for both the hole injecting layer111 and the hole transporting layer 112 at the same time. Accordingly,an element was manufactured easily and it was also possible to improvethe use efficiency of the material.

Example 12

When a composite material of a material having a high hole transportingproperty and an acceptor substance such as molybdenum(VI) oxide is usedfor a hole injecting layer of a light-emitting element, a material thatforms an electrode can be selected regardless of a work function;therefore, the composite material is extremely useful. However, whenlight emission is taken out from the anode side, light transmittedthrough the composite material is extracted to the outside through alight-emitting element; therefore, there are some cases where alight-emitting element is affected disadvantageously depending onabsorption characteristics of the composite material.

FIG. 28 shows wavelength vs. transmittance characteristics when NPB andαNBA1BP, which is the triarylamine derivative described in Embodiment 1,are each co-evaporated with molybdenum(VI) oxide. In FIG. 28, ahorizontal axis represents a wavelength (nm), and a longitudinal axisrepresents a transmittance (%). Vacuum evaporation of NPB and αNBA1BPwith molybdenum(VI) oxide was performed over a quartz substrate so thatthe mass ratios of NPB: molybdenum(VI) oxide and αNBA1BP: molybdenum(VI)oxide are each 4:1. The thicknesses were each 50 nm. Each transmissionspectrum of the quartz substrate is subtracted from the total spectrum.

It is understood from FIG. 28 that the film of the composite materialusing NPB has broad absorption in the wavelength range of 420 nm to 550nm. The absorption in the wavelength range of 420 nm to 550 nmcorresponds to regions where blue light to green light are emitted, andwhen the composite material is used, light emissions from alight-emitting element emitting blue light to green light are absorbedby the composite material. Accordingly, there is a concern that anadverse effect might be caused on chromaticity and luminous efficiency.On the other hand, it is understood that the film of the compositematerial using αNBA1BP has broad absorption on the longer wavelengthside than the wavelength of 700 nm. However, since the absorption regionis not a visible region, there are a few influences on a light-emittingelement.

In such a manner, since the composite material where αNBA1BP, which isthe triarylamine derivative described in Embodiment 1, andmolybdenum(VI) oxide are co-evaporated has little absorption to visiblelight, it was understood that the composite material can be preferablyapplied to light-emitting element emitting any visible light.

INDUSTRIAL APPLICABILITY

In a triarylamine derivative according to one embodiment of the presentinvention, energy gap is large or there is an energy difference(hereinafter also referred to as triplet energy) between a ground stateand a triplet excited state; therefore, the triarylamine derivative canbe very preferably used as a host material or a carrier transportingmaterial (especially as a hole transporting material) of alight-emitting element providing blue fluorescence or a light-emittingelement providing green phosphoresce. In addition, the triarylaminederivative according to one embodiment of the present invention can beused as a host material or a carrier transporting material of alight-emitting substance having emission wavelengths in a wide visibleregion (from blue light to red light), whereby light can be emittedefficiently. Moreover, in the case of forming a light-emitting deviceincluding a plurality of red, green, and blue pixels, a host material ora carrier transporting material can have the same kind also in a processof forming a light-emitting element; therefore, the process can besimplified and the use efficiency of the material is also high, whichare preferable. Further, the triarylamine derivative according to oneembodiment of the present invention can be used as a light-emittingsubstance and in that case the energy gap is large as described above;therefore, a light-emitting element with sufficiently short wavelengthsand high color purity for blue light emission can be obtained. Then,since the triarylamine derivative according to one embodiment of thepresent invention has excellent characteristics as described above, alight-emitting element having preferable luminous efficiency can beprovided, and thus a light-emitting device that consumes less power canbe obtained. Besides, since light emission having high color purity,especially preferable blue light emission can also be obtained, alight-emitting device having excellent color reproducibility and highdisplay quality can be obtained. Further, a lighting apparatus thatconsumes less power can also be obtained and in that case the lightingapparatus can be thin with a large area.

The present application is based on Japanese Patent Application serialNo. 2008-129991, 2008-300827, and 2009-022314 filed with Japan PatentOffice on May 16, 2008, Nov. 26, 2008, and Feb. 3, 2009, respectively,the entire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A light-emitting element comprising: a firstelectrode; a hole transporting layer comprising a triarylaminederivative over the first electrode; and a second electrode, wherein thetriarylamine derivative is represented by a general formula (G1),

wherein Ar represents any of an unsubstituted phenyl group, anunsubstituted biphenyl group, a substituted phenyl group substituted bya phenyl group, and a substituted biphenyl group substituted by a phenylgroup, wherein α represents an unsubstituted naphthyl group or asubstituted naphthyl group substituted by a phenyl group, wherein βrepresents hydrogen, wherein n and m each independently represent 1 or2, and wherein R¹ to R⁸ each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, and a phenyl group.
 2. Thelight-emitting element according to claim 1 wherein the triarylaminederivative is represented by a formula (31) or (32),


3. The light-emitting element according to claim 1 wherein thetriarylamine derivative is represented by a formula (33) or (34),


4. The light-emitting element according to claim 1, wherein thetriarylamine derivative is represented by a formula (40) or (41),


5. The light-emitting element according to claim 1, wherein thetriarylamine derivative is represented by a formula (43) or (44),


6. The light-emitting element according to claim 1, wherein the layerfurther comprises a fluorescent light-emitting substance.
 7. Thelight-emitting element according to claim 1, wherein the layer furthercomprises a phosphorescent light-emitting substance.